[The] Queen's [B]irthday (Titles should be capitalized except for connecting words like "to" or "and")

[The] Queen's birthday is the day chosen by some countries of Commonwealth to <s>celebrate officially</s> [officially celebrate] the birthday of the Queen or King.

The birthday of the sovereign was marked the first time in United Kingdom in 1748 by <s>the</s> [usually monarchs are simply addressed by their name and title, we wouldn't call her "the Queen Elizabeth," but simply "Queen Elizabeth"] King Geoges II. Since then, the date of [the King or Queen's] birthday<s> King or Queen have</s> [has] been set i<s>n all </s>[across the entire] <s>british empire</s> British Empire [British Empire should be capitalized]

Today the date varies depending <s>the countries</s> [on the country] and it is fixed <s>in</s> [at the] end of May or at the beginning of June in order to have <s>a </s>[weather is not countable thus you cannot use the indefinite article "a" with it] good weather. In some countries, it is a public holiday.

[Note that when you use a comma, it is improper to add a space <em>before</em> - it only goes <em>after</em>. For example: "I am happy to see you, mother." is correct whereas "I am happy to see you , mother" is not]

Birthday

Hi Mat!

I think your idea [don't need to capitalize idea] to pay for Fiona to try an extreme sport is really good because she likes unusual gifts and extreme sports. I advise [advise is grammatically fine and understandable, but it would sound more natural to say "I would suggest you give her"] you to give her a certificate for a parachute jump because I know she's been dreaming about this for a long time She will be happy!

By the way recently I also had my birthday. It was a couple <s>a</s> of weeks ago. I usually celebrate my birthday twice First time I celebrate with my relatives and second time with my friends.

I got a lot of presents.The better present <s>gave</s> [was given to] me [by] my friend Mary. Her gift was a guitar! I was so excited about it. And now I [will] learn to play.

The Day I Joined ElS School.

On February 5th, 2020, the day I joined ELS was an amazing day. When I came to ELS, I did not know my teachers. I also did not have any friends. In the first period, The teacher introduced herself, and she told <s>every</s> all of the students to introduce <s>them self</s> themselves. After that, she started explaining the first lesson, and her <s>explain </s>explanation was very clear for all of <s>student</s> the students. After that, we had <s style="color: rgb(230, 0, 0);">a</s> breakfast. I sat on my chair, and I drank my coffee. I started to talk with my classmates, and I made a friendship with them [this is grammatically fine but English speakers would be more likely to say "and I made friends with them."]. All my classmates were friendly. The second period was reading and writing. The <s>teacher</s> teacher's name was <s>terry</s> Terry [remember to capitalize names], and her class was interesting. She made us <s>enjoyed in</s> enjoy her class. After that, I had a <s>break lunch </s>lunch break, and I went to <s>the</s> <s>MacDonald</s> McDonald's restaurant. I saw my classmate there, and we ate our lunch together. The ElS place was near <s>to</s> a lot of restaurants and cafe, and I liked its <s>place</s> location [this isn't grammatically wrong, but a native speaker would use the word "location"]. I will never forget that day because <s>I</s> it was really interesting.