Relax sweetie, he won't be any better or any more experienced than you will, while you're nervous and wondering if you're doing ok, he'll be too busy feeling the exact same way to judge you on your kissing ability, so there's no real pressure.
The way for anyone to learn to kiss is they way you guys are doing it now, just experimenting on eachother.
First, your lips will meet, then from there its all about taking signs and cues from eachother.
Its not one, big, long, open mouth kinda deal, making out is like a series of smaller kisses joined together.
Start with a few slow, on-the-lips kinda kisses, pressing a little harder each time, then open your lips a little bit the next time you kiss him, kind of taking your lips in his.
By this point, he should be taking the hints and kissing you back and from then on in, it'll all take care of itself.
The funny thing is though sweetie, with young boys, you can be the greatest kisser in the world, but chances are, the first thing he's gonna do is stick his tongue in your mouth and start going crazy, so like I said, dont expect to have to work to hard to impress the guy :)
Good luck though sweetie, happy kissin' :D