HOW TO MAKE MY COMPUTER RUN 8GB RAM?

I HAVE WIN7 64BIT AND EMERY ASUSTEK MOTHERBOARD BIOS VERSION 3.15 WITH A PENTIUM D 2.8G CPU...NOW GLARY UTILITIES DOES SHOW CPU GENERIC NAME AS ( X86FAMILY 15MODEL 4 STEPPING 4) MEANS NOTHING TO AN OLD MAN LIKE ME...PLEAE ADVISE THANKS