how to format drive

Hi.

I just bought a Dell inspirion mini notebook at Sam´s. It was a returned item. My problem´s that it has a password and I can only get in as a guest, with limited access.

How can I run a full recovery, formatting the disks and all old information in it?

I´ve had tried ctrl+f11 but nothing happens. I have the recovery cd, but there is no cd driver.