Have to agree with what the guys above have said really. I guess a lot of it depends on the strengths and weaknesses in your game. Realistically, the only position you can play is 9. Possibly wing. I know it sounds obvious, but the main issue you will face is that you haven't played the game on a consistent basis which will effect your ability to play in a key position. It's all well and good throwing a smaller guy in at 9 simply based on physique, but you have to be able to read the game as well.
The key to playing at 9 is the ability to make the correct decisions. Pace isn't crucial, but you need to be able to make good decisions at pace. A lot of that comes with experience. Everything your team does in attack comes on the back of what you do, which means your passing game off either hand needs to be up to the mark. You can have the quickest and most intelligent back line in the game, but that doesn't count for anything if you are passing the ball to the ground. As I said before, if you have pace on the back of that then great. If you can mix things up, naturally you are harder to defend against which leaves holes and opportunities open elsewhere.
The best advice I can give to a newcomer is watch as many games as possible and work on the fundamentals aspects of your game. Hard work always pays off.