Problem Loading Linux

I have Linux on an image in my cd-rom drive.

I have previously loaded Windows XP but couldnt use it because I had already installed it on another PC - so I want to remove this and load Linux.

I am fairly PC illiterate when it come to dos-commands and such...

HELP!!!

You did not specify which distribution of GNU/Linux you have on CD.
Usually all that is necessary is that you boot from the CD, then follow the on-screen instructions for installation.
For the most part, all good distro's have basic setup instructions on the website. It is always best to first look on the developers site for setup how-to's.