Most likely, your computer is not a CD-RW burner, so it can play it, but not edit things on it. My suggestion, put it into a CD-RW burner or DVD Player with burner, then try again.
Open "My Computer" on the Desktop, right click on the disk you want to format under "Hard Disk Drives" and then click on "Format". Select the required options and then click on "Start"...
Boot up the computer in command prompt mode. Go from there. 'format c:' is the command. Make sure you have an operating system to reisntall.
Answer 2
Depending on which operating system you are...