In this case I am the dummy. I'm going to try for a football team and wondering whether you guys can give me tips so i won't embarass myself. I've got a lot of explosive speed, and my track coach told to try for a local so I can put the speed into practice.
I know nothing about American football, but when I started playing rugby a year and a bit ago I went out with the same outlook; very quick and agile and all. First learn how to take the pain and tackle hard, then start making them look like lumbering fools.
If you have speed you'll more than likely be a receiver, aslong as you can catch the ball, so your main focus is getting into open space, catching the ball and getting it up the field. If your path is blocked, just fall to the ground, and avoid dropping(fumbling) the ball at all costs.
Other than that, don't be scared to take a hit, just learn to anticipate it.
have explosive speed is good for football because a lot of positions (on offense and defense) require you to have that burst.
how much do you know about american football?
would you prefer to throw/catch/run the ball? or tackle people?
and you dont have to worry about embarrassing yourself, just go to the tryouts, show them the explosive speed you say you have and do a couple drills. maybe try a position here or there and you'll do just fine