Don't worry about "being thick" - we were all there at one point. That's why these forums exist, so that we can learn!
Do this one first: http://download.gigabyte.eu/FileList...68m-s2p_f3.exe
Then turn the system on and make sure that it works normally.
Once you're convinced that it's working right (an hour or two at most), then do this one: http://download.gigabyte.eu/FileList...68m-s2p_f5.exe
Follow the directions EXACTLY. If unsure, don't do anything until you review the documentation.