Presumably you’ve gathered from scouting the forums that there’s a pretty loose procedure for creating music. Upload it somewhere and post to this thread:
Then it’ll be reviewed and added to an approved submissions playlist. Then probably sit for a while because the part of the game it’s for will be a long way away.
It’d be great if you wanted to work on sound effects! If you do, start a new thread in Sound and I’ll give you a rundown of what needs doing.