What sort of music d’you want to play? Once you got that worked out, start gettin’ to know people in that scene. Go to gigs, talk to the people around you in the audience, talk to the bands, talk to the people workin’ at the venues. Meet as many people as you can, and you never know – maybe you’ll find a band lookin’ for a guitarist, or some other people tryin’ to start a band, or someone who’s never even thought about bein’ in a band, but might give it a try. The key to gettin’ started is workin’ out what you want, and then talkin’ to people!
If you get to know the right venues and record shops, you might try puttin’ up advertisements there, too. I know a few bands that found singers and drummers and that sort of thing by puttin’ posters in shop windows. You got lots of options!
Whatever you decide to do, congratulations on workin’ hard enough at guitar to feel ready for a band, and good luck!