you probably wanna check out all your open chords, chord scales, and cadences. thats a basic approach to songwriting. i thing the easiest was is to just mess around with chords and riffs for a while when your play (maybe record yourself messin around) and eventually you'll hear something you like. take that and work off of it. a standard song goes something like intro, verse, chorus, verse, chorus, bridge, chorus. try that out

pat