When I play games, I understand that you have to focus and think more carefully about what the next step you want to take is. Also, you should not give up if you make mistakes which lead you to lose, but you should learn lessons from those mistakes.

A small girl in second grade got hit by a car near in the/my neighborhood. She broke her leg. My mom and I felt very sorry for that poor girl. Mom said she could not go to school for at least a month, “Such a talented girl, not able ("unable" is probably better here) to go to school,” she sighed dramatically. I thought that it was important for the girl to rest for a bit, besides she is still a kid so she would love not going to school. I think it’s actually a good thing for her to relax a bit. 

An exhibition dedicated to red-haired people

An exhibition called "Roux ! De Jean-Jacques Henner à Sonia Rykiel" is taking place in Paris until May 20th at Jacques Henner's museum.

Ginger-haired people represent 2% of the population, however, some of them are still victims of stigmatization, jokes, superstitions or legends [1]. The exhibition taking place in Paris highlights paintings or art pieces whose characters are red-haired (people). The exhibition gathers hundreds of objects from album covers to posters or paintings.

Painters appreciated red-haired people because their hair had many shades. Some of the painters, such as Henner used colors such as blue or green to highlight the red reflection.

The exhibition is not only limited to painters such as Henner or Auguste Renoir, it also highlights modern heroes whose hair is red such as Tintin or Spirou. It also deals with fashion designer Sonia Rykiel who is also red-haired. She has always designed clothes which could fit and highlight red-haired people.

Then, during the exhibition, there are literary extracts from Charles Beaudelaire, Guy de Maupassant or Emile Zola. Those authors depicted red-haired characters in some of their masterpieces.

This exhibition is a good thing because red-haired people can live [2] hard moments - at least in France. Indeed, unfortunately, they are often laughed at because of their hair and they often have to hear bad jokes or prejudices. For example, some (stupid) people believe that red-haired people smell bad, that they are dirty. This stupid and uneducated behaviour can lead to harrassment, especially in school. I have just finished to read reading [3] a newspaper article about red-haired people being harrassed because of the color [4] of their hair and it made me sick. Some of them even thought to die or some women told they cried while being pregnant wishing their newborn will not be red-haired.

How can this discrimination go so far? How come nothing has been done to stop it? Why is it that deeply accepted in our culture? I don't know. I hope that this exhibition will help a bit.

Fortunately, not all red-haired people have been harrassed and some of them live peacefully in our society. Let's hope that mentalities will improve with time. Discrimination is a real plague in our society.

[1] The word "legends" is ok here but "myths" might be more appropriate

[2] "Go through" would be better than "live" here - "red-haired people can go through hard moments"

[3] "To finish doING something." Also, "To continue doING something," and "To like/dislike/enjoy/hate doING something"

[4] Just so you know, "color" is an American spelling and "colour" is British English. It's the same for "favorite/favourite" and probably some others that I'm forgetting. What you wrote isn't wrong though

Sherlock Holmes ''The dying detective''

Mrs. Hudson came to see Dr. Watson and talked [1] to him about Holmes’ condition. John Watson is his best friend and they often investigated crimes [2] together. She told him that Holmes was sick for three days and he didn’t want to see any doctors. Watson was horrified to hear that and they both went to Holmes’ place. During the car trip, Watson asked for details and Mrs. Hudson told him Sherlock contracted his illness working on a case.
When Watson saw him from with his own eyes, he was shocked. Holmes had fever, red cheeks, a feeble voice, he looked weak. At first, Watson wanted to see Sherlock closer, but he did not have the opportunity to do so, Holmes said to him his illness was very contagious by touch. John said that because of the sickness, Holmes was not acted acting like a grown up, but like a child, and it was his duty, as a doctor, to take a look at him. Holmes snapped back that if he had to have a doctor, he wanted to choose someone he trusted. John Watson was a bit offended, but Holmes said he was only a general practitioner and he wanted to see a specialist of exotic diseases. Holmes was exhausted and he asked to Watson to continue the discussion two hours later [3], leaving him time to rest.
Two hours later, they resumed their conversation, Holmes asking to Watson to do unlikely things that did not seem to have make any sense. After this typical Sherlock Holmes moment, he finally said to go fetch Mr. Culverton Smith, a specialist of Eastern diseases, and told him the address. The mission by Holmes to Holmes' mission for Watson was simple : bring Mr. Smith to Holmes’ place and hoping in the hope that he would be able to cure him. Holmes’ life depended on it. Watson, by all means, had to convince him to come despite the issue between Holmes and Smith.

[1] Your sentence makes sense but I think "and speak to him..." would sounds more natural

[2] Be careful with tenses. He IS his best friend so they INVESTIGATE crimes together

[3] It's more natural to say "continue the discussion IN two hours"

What happens if you find a treasure?

Situation n.1 : if you find a treasure in someone else's house
According to the French law, the value of the treasure must be shared between the person who found it and the owner of the house. For example, in 2016, workers who were repairing a fireplace (chimney?) [1] discovered behind it a box in copper copper box. They shook it and discovered 600 coins dating from 1870. Those coins were valued at up to 100,000 euros. The justice judge/court [2] decided that the amount of money should be shared equally between the workers and the owner of the house.

Situation n.2 : A treasure at home
If you find a treasure while gardening, it belongs to you. You have the right to keep it unless it has an archeological value.

Situation n.3 : A treasure at home with an archeological value
If it has an archeological value, you must call the authorities. They will have the right to keep your discovery for up to [3] five years maximum and in the end, they can offer to buy it to from you (or you can keep it if you refuse).

Situation n.4 : Using a metal detector
If you use a metal detector, the law considers that it is not a discovery "per chance" and you'll have to give what you have found to the authorities. If you don't, and if the authorities discover you kept this treasure for yourself, you'll risk having to pay a huge fine.

Situation n.5 : .... and if I find some petrol?
The state will take your property claiming that it is its theirs. You'll have but no choice to leave your property.

I have never found a any treasure. The only things we have found at home in the garden were old horshoes and rusty irons...

[1] Both work but they're different things

[2] "Judge" and "court" make sense here. It depends on the case/situation

[3] This just sounds more natural

working in a group or individually?

[a writing practice]
For me, working in a group may be a better choice for the following reasons.
First, the assignments can be done more efficiently because the work will be is assigned partially to different members. Every member can simply finish their part to get the work done. Thus a lot of time can be saved.
In addition, we can learn mutually with our teammates. We may get new ideas when we are/get stuck. It’s fascinating to find out different thoughts about a the same subjects. and also we can get help from the ones those who are more experienced than us and, thus, achieve better.

The word "thus" is used correctly here but it's not used very much casually. In both of the places you've used it here it would be fine to just leave it out completely. Good work though