IBM-THINKPAD PROBLEM

Hi,
I have an IBM – thinkpad computer. In the process of learning Wins 2000 pro, I deleted an important boot file which made the computer impossible to boot. I need to change the start up to CD rom to enable me repair the operating system. I do notknow how to go about it as I am not used to the system. Right now, my activities have been cripled. I need somebody to direct me on how to go to the BIOS setup and change the start up to CD Rom to enable the system boot from the CD.
Thanks

Emeka Onyekwuluje
Emekaco@yahoo.com