Corrections in red. Stylistic changes to make it sound a little more natural in blue.
It is my first visit to this site.
Today I woke up very early, and understood that I want to improve my knowledge of English. I have been searching for the best site during the year, and I have found it! )) I also I think that there I can find a lot of useful information and partners to talk with here.
I am a student, and in the near future I will have an exam. I hope that I can practise English here and will pass the exam!)
At your age it is more appropriate -- at least in American English -- to call a person of your age (17) a student, rather than a pupil. If you were about 12 or younger, I would call you a pupil. Also, in American English, we write practice. However, British English "practise" (as a verb) is perfectly correct.
You write very well.
