Go Gwolf! It is great seeing younger people start playing D&D these days. I have been desperately afraid that they would all be lost to computer games.
I'll offer one piece of advice that I haven't seen so far: Read the Story Hours. There is a lot of great material in there about building good plot arcs. Steal from them if you want to.
If I'd had access to Story Hours like the ones on this board when I was your age, I'd have become a good DM long before I did.
I'd like to think that I have a pretty good Story Hour going, but if you can only read a few, ignore mine and read Sagiro's, Pirate Cat's, Wulf Ratbane's, Dr. Midnight's and Old One's. Your time will not be wasted and you will get a great education about how good a game this can be when done perfectly.