When you have booted up the computer from the OSX disc, and get beyond the license information. You'll be able to select the tools menu at the top from there select disk utility.
Highlight the disk drive in the left hand pain and select partition from the top center screen. From there you should be able to figure out where/how to reformat (I'm doing this on memory). Here's a link that I found instructing you how to do this by googling. linky
Highlight the disk drive in the left hand pain and select partition from the top center screen. From there you should be able to figure out where/how to reformat (I'm doing this on memory). Here's a link that I found instructing you how to do this by googling. linky