Original post by: Sam Freeman ,
To use the install cd, insert it while the laptop is shut down, and press the C key immediately after the laptop starts up and keep it held down until it boots. If that doesn't work, then you can create a bootable USB installer for Mac OS X (there are lots of good articles on google) by downloading an installer onto another computer. Then, you can boot from the installer USB by pressing the option button while the laptop is starting up to select it. Good luck!