It depends on what kind of song you're trying to write. If you're writing a punk song, then there's basically just verses and choruses. But if you're trying to write a complete song, do what I do and use what I like to call, "the everyday kickass Metallica song." This setup for a song is what most of Metallica's songs are in. This is how it goes: intro, verse, chorus, verse, interlude, verse, solo, chorus. If that seems to difficult and you're a beginning guitarist, just go with the extremely easy punk song stuff. And if you don't really care much for any of those, just listen to one of your favorite songs and look at how that is setup, and try to do something similar.