Welcome to My Guitar Buddies, Callan!
That's a GREAT question!
I would suggest you get a multitrack recorder, so you can record what you play, then play it back to review it, and change or add other parts to it, until you find what you're trying to do.
As far as putting music that works together, you're kind of on your own, because what might sound good to you, may not sound good to someone else. That's why you'll just have to experiment, have fun, and go from there.
Good Luck, hope this helps.
Thanks. 
