I've had many discussion with guitar player / singer about how to sing along when playing. Most of the time it went down to learning the guitar parts so well that you don't have to thing about it. Then you can concentrate on your singing.

Having said that, creating music that will fit your lyrics can be very hard to do. I know I can't lol . I'm mainly a guitar player and altho I have a good voice, I've never learned to use it correctly.

One thing you can do right away is to try to hum a melody over the lyrics you've written. As you learn the open chords, you'll be able to play those melodies you were humming. First thing you'll know you'll create chord progressions that will fit with your lyrics. It sounds easy when I say it like that but it's not always the case :)

Give yourself time to learn those chords and in the meantime try to come up with melodies over your lyrics.

Let us know how things work out as you go.

Good luck.