Does it start at all??
If so, when you power it on, you will need to look quickly at the bottom left of the screen to see what to push to enter the BIOS (Basic Input and Output System). It may very well be ESC, as that is what it is on my HP. Once you are in the BIOS, you will need to find the option of Bootable device. (F9 on mine) and choose that. Then you need to choose your CD drive as the boot device.
Once your in, just follow the on screen directions.