How can I delete my hard drive?

I have been trying non stop for over 2 days now to no avail. I FINALLY found my Vista disk but once prompted to select my driver to install to It finds none. Can someone either A find a solution to my problem or B tell a complete retard how to delete my hard drive. I mean STEP BY STEP details, so far NOTHING i have found on the internet can help me...am i just stupid?