Depends on what you mean by "scrolling background". For a shmup I would just have the background tiled past the end of the window. For example, a window 1024x768 tile1.x would start at 0, tile2.x (same image as tile1) would start at 1024, both tiles will move by whatever increment towards the left,
simplified:
while gameisopen
- increment tiles
if tile1.x == -1024 (offscreen) then tile1.x = 1024
if tile2.x == -1024, then tile2.x = 1024
end while
It can probably be even simpler.
For an adventure type game, you could do it as model76 explained.
What is "this project"? Information is good.