If I were you, I’d find someone who knows how to do it, and work with them. There are a lot of nuances—major and minor chords and using the seventh and then there’s the issue of how the music flows.
If you are doing something simple, like rock, then you can get away with what @Atomic suggested. In fact, it may be as easy as going back and forth between two chords, or only using one chord. Rock music usually uses two chords and goes back and forth between them. Once you figure out which two you want, you just go back and forth between them for the whole melody.
If you’re doing anything more complex than that, I really think you need to learn more, preferable with a person.