I think you should keep your essay in past tense even though you might still doing it (but it just a suggestion, you don't have to take it)
The busy, tired and stressful week turns into a fun and relaxed week, after I play cricket with my friends every Tuesday and Saturday.
Just my suggestion: The busy and stressful week became fun and relaxed after the weekly cricket games with my best friends.
My friends and I gathered fifteen people who are interested in learning and/or playing cricket
I am a fast bowler, and can pitch bowl at least 80+ mph. I am also improving my batting and fielding skills
Another suggestion: Even though I can pitch bowl at 80 mph, but I am also trying to improve my batting and fielding skills (I have no idea if this even grammatical correct)
Some of my friends had a hard time playing because of the level of difficulty
inof the game
I tried to teach them the important details to the best of my ability
and to help them increase their confidence
When I will turn eighteen, I will start playing for Dayton Cricket Club
Yet another suggestion :) : My goal when I turned eighteen is to play for the Dayton Cricket Club.
I know grammar is not my strong forte so I hope someone can help improve your errors and maybe even catch some of mine.