Well Gather round children
Basically, Get some sizzors and cut them out, If your really sad like me you can file off the little bits that remain after you cut them.
Basically put the plates into the frame and then take one of the clips, You will see one is sorta hooked and one is more of a L shape. The little hooked shape folds around the edge behind the plate frame Then you just snap the L shaped side over the frame so it over laps the numperplate a wee bit and slide it into position, You will find that, Say your fitting the plates onto a rounded surface such as the front big bumper of a MK2 that when you put both screws in the frames will sorta bend round the bumper, The plate however seems to sorta stick out at each side. So you use the little hooks to hold in the plate at each side so it doesnt stick out from the frame.
And if that didnt make any sence at all (because im in a rush, my girls nagging me to take the dogs for a walk) ill post pics when i return