how can I make the background scroll to the left?

BGOFS layer,x,y,z There's no time parameter, so you'll have to offset it every frame to make it scroll smoothly. The coordinates are the screen coordinates of the top left pixel of the background layer, so if you want it to go to the left, you'll need to use a negative x coordinate.

can you show me a screenshot?

Try using BGANIM command. The help screen shows 3 different ways to do it. Just pick one you're comfortable with.

You'll probably want to use BGSCREEN command as well, so you don't run out of screen too early.

Okay I would try