Seeing stuff here that I'm learning in my computer science courses makes me want to puke. >_< I should get out of this "I hope I'll never see this stuff again" mentality.
So, this grep thing. It takes a regular expression and searches for that regular expression in the given filename. A string of concatenated characters is a regular expression, don't worry so much about this. You can put pretty much any isotropic name into the place Titan has, and grep will search for it. Then, list the filename. The * in the "game*" is a wildcard; it will match any number of characters, so it should match specific game logs as listed by DStu. I forgot what the -l is for. grep has a bunch of options, you shouldn't need them. "grep.exe -l ISOTROPIC_NAME "C:\PATH\TO\THE\GAMELOGS\game*.html" should work.
About cd, make sure the path is something like C:\PATH\TO\PLACE\YOU\INSTALLED\GREP.
Hard to explain this stuff, computers are tricky machines they are.