Need help with camera.

[byu rocks23]

I'm making an fps where the camera turns with the mouse. I want to pretty much copy the function "let the mouse orient the camera" except that you don't have to click and it works vertically. So far i can get the camera to turn right by doing the function- turn at speed right speed=[mouse distance from left edge]. This works but I can't get the camera to turn left because there is no mouse distance from right edge. Same thing with no function mouse distance from bottom.