Contra Style Shooter

what’s up fam!!! haven’t posted in a while, but here it goes. i’m trying to figure out how to make the scrolling background from the underground maze levels in the original contra. u know the one where you are behind the laser barrier and you have to shoot the targets to proceed. i got the characters / background designs, but i don’t know how to make that work. should i use AS for the forward movement or tween it somehow. any help would be appreciated.