k.. if you want to just do a fresh install, no problem.
#1, make sure you have everything you want to keep on your drive, saved someplace other than your computer. So like, online, or on an external drive ect.
-Just boot the install disk. A DVD icon should pop onto your desktop(sometimes it comes up on its own).
-It should have an icon that says Install OSX. Click that, and after the first prompt comes up, go to the advanced option. There should only be 2, upgrade and tools or something.
-Then you need to go to disk utilities, so you can erase the drive. Sometimes you have to restart before it allows you to do it. Now just erase the drive and from this point, you can't go back until the MacOSX installation is complete.
The rest should be pretty self explainable, it will basically restore a clean installation onto the drive.