Need help reinstalling OS X 10.4.11 on iBook

My cousin bought an iBook at a garage sale and it is full. It is only 40GB and only has put on 4GB of songs and pictures. There should be lots more room left and I can't figure out where all the space has disappeared to.

Anyway, I tried to reinstall with an OS X 10.4.6 DVD and it just hangs on reboot at the apple logo, but no spinning wheel shows up. I let it sit for over half an hour with no progress. I then tried turning it off and pressing the C key to install, but same thing.

Am I doing something wrong during install? Is there a utility/command to free all disk space?

Sorry for the newbish questions, but I'm new to Mac.
-=Mark=-

Did the 10.4 DVD come with the iBook? If not, what DVD is it? A gray DVD or a Black one?

It is a backup dvd. I'm pretty sure it's a retail apple DVD. It doesn't look like a special iBook disk.

some other info on the ibook. it says PowerBook 2.2 with a Power PC 750 @467MHz and 320MB ram and I think a 20GB hard drive.

on the bottom of the iBook it says model number is M6411.

I just called my cousin and had him check.

-=Mark=-
ps, the disk is hand written and says "os x 10.4.6 tiger" and it's updated to 10.6.11

pss is there a way I can look on the DVD for a type?