I have made a smoke particle effect that I instantiate everytime the player shoots, its working but can not be seen with the background. If I delete the background it's visible, I've tried changing the ordering layer, creating a new layer and putting it above the default, but no matter what it's still below the background. Any ideas?
Assuming you are developping a 2D game, you can use the z axis to set the distance of the elements to the camera (what will be the equivalent to the order of render)
Usually in a 2D game you will have the main camera at -10 in the z axis. So moving in the inspector the backgroun to, lets say z=5 or z=10, and keeping in you particle system in z=0 should solve your problem.
Try this easy trick and let me know if you are still facing problems.
You can check the second half of this video for a better understanding