well, first make sure you have WinZip, when you download it, and install it, you can now unzip the downloaded client
but before you unzip it, make a folder called GC, and put that folder in the C drive, but NOT in any other folder, Then make another GC floder, and put that folder in the previous GC folder, then unzip your files there
you can either do by opening it regularly and choosing "unzip" across the top(or that is how it is with my version)
or you can right click and there should be an option to unzip
either way, make sure your files from the client are under C:\GC\GC