Dear Mike,
Thank you very much for your letter. My name is (твоё имя). I'm (твой возраст числом) years old and I live in (город), (страна). In my spare time, I like to play video games, but I wouldn't call it my hobby. What I'm actually keen on is photography. I am still a beginner, but I am working hard to improve my skills. Unfortunately, I'm not a big fan of sports. Although I am not an active person, I can swim pretty well. I can play football, too. It used to be my favourite outdoor activity in the childhood. What about you? Did you play football when you were a kid or did you play something else?
Bye for now. (или любая другая завершаюзая фраза)
(Твоё имя)