Guide to enjoy Granada within twenty four hours (please, I need help with this little text!)

First of all, we have to say that it is not possible to know a city like Granada in such a short period of time. However, I am going to give some advice about what to do in this city if you cannot stay there for a long time.

It is obvious that the most impressive monument in Granada is the Alhambra. Nonetheless, visiting this palace takes a lot of time and it is a tough activity, but, without any doubt, it is worth it. If the tourist decides to go into the Alhambra in the daytime, I recommend resting in the night (maybe a little ambiguous or it's just me. Do you mean to say that you recommend resting in the Alhambra or do you mean resting a lot prior to going because it's an exhausting experience?), for instance, and then going to some restaurant in the centre of the city. Otherwise, if the decision is to not go to the Alhambra, I think that the best choice is walking around the neighborhood Albaicín, where we could find some remains of the Arabic culture as well.

On the other hand (this is a more common expression), Granada has an idea location to do short trips to nearby places. Firstly, it is possible to go to the beach in just an hour by car and there is a wide range of destinations to from which to choose, like the coast of Málaga, the most well known of them. Secondly, there is a mountain range called Sierra Nevada less than thirty kilometres from Granada, where people go to skiing or snowboarding.

To sum up, Granada is full of possibilities to have a good time, even if you have only one day to stay there.

Well done! Some of my "corrections" are not really corrections, but more so suggestions. Your English is superb; keep practising. 
I'm actually going to Granada pretty soon (and shall only have a day to be there) so this was a nice read. 

Guide to enjoy Granada in twenty four hours (please, I need help with this little text!!)

First of all, we have to say that it is not possible to discover/visit a city like Granada in such a short period of time. However, I am going to give some advice- about what to do in this city if you cannot stay there for a long time.

It is obvious that the most impressive monument in Granada is the Alhambra. Nonetheless, visiting this palace takes a lot of time and it is a tough/demanding activity, but, without a doubt, it is worth it. If a tourist decides to visit the Alhambra during the day, I recommend resting at night, maybe going to some restaurant in the centre of the city/city center would be a good idea. Otherwise, if the decision is/if you choose/prefer not to go to the Alhambra, I think that the best alternative is walking around the neighborhood Albaicín, which is quite interesting also thanks to some remains of the Arabic culture.

Moreover, Granada is a privileged location to do short trips to nearby places. Firstly, it is possible to go to the beach in just an hour by car and there is a wide range of destinations to choose from, being the coast of Málaga the most renowned among them. Secondly, there is a mountain range called Sierra Nevada within thirty kilometres from Granada, where people can go skiing or snowboarding.

To sum up, Granada has plenty of possibilities to have a good time, even if you have only one day to stay there.

p.s. : What a wonderful photo !, I wonder whether/if you are the one who took it

Guide to enjoy Granada in twenty four hours (please, I need help with this little text!!)

First of all, I have to say that it is not possible to know a city like Granada in such a short period of time. However, I am going to give you some advice about what to do in this city if you cannot stay there for long. 

It is obvious that the most impressive monument in Granada is the Alhambra. However, visiting this palace takes a lot of time and is a tough activity, but, without doubt, it is worth it. If a tourist decides to go to the Alhambra during the day, I recommend resting at night and perhaps going to a restaurant in the centre of the city.  If you decide not to go to the Alhambra, I think  the best alternative is walking around the neighborhood Albaicín, where you can also find some remains of the Arabic culture.

On the other hand, Granada's location is ideal to visit places nearby. Firstly, it is possible to go to the beach in just an hour by car and there are a wide range of destinations to choose from on the coast of Málaga. Secondly, there is a mountain range called the Sierra Nevada  less than thirty kilometres from Granada, where people can go skiing or snowboarding.

To sum up, Granada has plenty of possibilities to have a good time, even if you have only one day to stay there.