#1
Im writing a punk rock song. I wrote a riff but its the intro and chorus. How would i decide on a chord prog. For the verse?
#2
Do you have a melody?

The easiest way to write a chord progression for a song is to harmonize the melody. That is to say, you pick chords which contain the notes of the melody. You use your ear and knowlege of theory to pick WHICH chords which contain those notes are the best choices.