Need help on how to use the FISKARS 6 1/2' ruler?

I don't know if the white paper on the back is to be removed or not. And how do I measure material with it? The ruler has markings on ir, but I don't know how to mark my material by the markings on the ruler . If any one has used one and know how to use it please let me know. I am having a hard time cutting out squares , half squares & ect to make a quilt top . Just if I knew how to use the ruler it would help a lot. THANKS FOR YOUR HELP.