Refer again to my previous post. ScrollX and ScrollY are used if your layout is bigger than your screen and you want to show different parts of said layout. If you just want an infinitely scrolling background, then there are a couple basic ways that could go:
1. Your background is a single tileable image that is at least as large as the screen in the direction you want to scroll. In this case, you have two instances of this background right next to each other in the direction of the scroll which wrap(by repositioning) to the opposite side of the screen when they're no longer visible. You need two instances for the case where one of the images is only halfway on the screen, so the other one is there to show the part of the image that's off the screen on the first instance. You manipulate the position of these images to simulate scrolling.
2. Your background is composed of small, distinct elements. In this case, you need enough elements only to fill the screen size, manipulate their position to simulate scrolling, then when they go off the screen, you wrapping(again, by repositioning) them to the opposite side of the screen.
I'm going to stress again, the only time you'll set the scroll values is when your layout is bigger than your screen size. If you have an infinitely scrolling background, this will have to be simulated by repositioning the background elements.
If you describe what you're wanting to do in more detail, it will be much easier for me to give a proper explanation. Detail would include whether or not your levels are static or procedurally generated and whether or not you want an infinitely scrolling background.