Im obsessed with the most amazing guy on this planet, help me!!!?

ask him if he has a girlfriend. if he has there's nothing you can do but if he hasn't ask him out and if you can't do it face to face do it by letter as you said. he might say no though because of the age gap (not that it is that big) but be prepared for that and don't get depressed or anything if he turns you down. One way of starting a conversation if you go to the same sports club is by complimenting him on his sports ability or something and then get a conversation going from that. good luck but if he turns you down you'll have to move on! x