I'm writing a ska song and i need to write a bassline

i just started writing so the guitar parts simple

the verse is: Dm then A
the chorus is: G then F

please help
With ska, you probably won't have to worry too much about the rhythm (straight eighth notes will do fine), but you'll want to be using notes from the guitar chords, plus anything from your key signature. You're really just writing a walking line in double time for ska, and walking lines aren't something you learn in a few minutes. Just mess around until you find something you like.

Quote by Applehead
There are some things in life that are universally "good":

Sex, pizza, the smell of fresh washing and slap bass.