Indie Basics

Hello


I hope you guys can help me. I'm a qualified and experienced musician as well as an avid gamer and so I want to try my skills in game music composition. However, I don't know where to start. I have 0 experience composing a game soundtrack. I don't even know how long this kind of composition has to be.
I'd rather be writing music for a specific game or at least a concrete idea with some visual art to aid the composing. I don't expect to earn money, at least not now.

I'd appreciate some help, even if it's a nudge in the right direciton