Introductions

hi, am trying to write a song for disaster can you give me some ideas?

Sounds like a terrible song disaster.  why not write one with victory. But here goes
Start with your key  ie G add the 4 chord and 5 chord  This gives you G C D  Add a relative minor of these chords which would be Em  Am  Bm
You now have 6 chords to play with. Add a few scales from those chords and hey ,....presto victory,....or disaster.