13, it's a great hobby, but it does take some patience to learn. Best way to do this is to find a local AMA (American Modelers Association) club and get them to give you instruction. You'll have to join the Association anyway to fly within the law and with insurance...I strongly recommend NOT flying with out insurance, I've seen many nasty accidents.

Today's radio's will most likely have a buddy hookup that will allow someone to "take control" if you are having a problem...this is the value of an instructor.

As Andrew and others noted, go to Hobby Lobby, Tower Hobbies, or any of those online retailers and look for a .40 2-stroke gas engine model - they'll list airplane kits specifically by engine size. ARF's (almost ready to fly) are great if you just want to get up and going with flying. They're relatively inexpensive, and you won't have the emotional attachment to a plane you took 6 weeks to build. So if it crashes, you get replacement parts, snap/glue them on and go again. I actually like the building aspect more than the flying, but I'm nutty anyway.

Post back a not if you think you like a particular plane/kit, and we'll let you know what we think. Don't forget the Radio/Servo costs, field kit, and all that.

Good luck!