How do I make background solid?

hello to all

i did a background tunnel 12000px, in the midle is nothing its the place where the player can fly, the background is done in one piece, but how to tell to the sprite when he collide then he die because actually its not working

http://s23.postimg.org/84fmp87ft/tunel.jpg

imothep85 you could use smaller invisible sprites at different parts of the tunnel and check those for collisions or to give the player the ability to fly...

Firstly, that's just not how you would make a level. At the very least you need to split it into smaller chunks and combine them. A 12,000 pixel background is going to cause you all kinds of problems on many devices and later in development. You could then use collision polygons and the solid behavior on each section. Otherwise, invisible sprites with the solid behavior overlapped over the background.