iceFlashEX1, the common method to add an infinite scrolling background is to create a Sprite object twice as wide as the layout, and add the bullet behavior. Then, once the Sprite object has moved halfway off the screen, you move it back to the original position.
Caveat: Depending on where exactly your background repeats, it may not have to be a full 2x layout.width. You would just move the sprite back to the original position whenever it reaches the repeat point.
Though, actually, now that I think about it... you might just be able to use the Wrap behavior with a single sprite with the bullet behavior. It'll be a good experiment to try.
I hope this points you in the right direction.