the download is an .iso file.
It can burned directly to a cd-r (or dvd-r ) as an image.
Do not burn it as a data.
If you don't have the software to do that , use imgburn (free )
ImgBurn Free Download and Reviews - Fileforum
To use Imgburn , put a blank cd-r in the drive. Do not format it - if autoplay pops up - just close it.
Open imgburn, Click "Write Image File to Disc" - browse to the repair .iso you downloaded.
When you have done that - boot the cd on the pc that is in trouble.
Windows will load from the cd into memory and it runs from there.
It only contains Repair tools - not installation files.
It won't do anything to your programs or documents.
It is used to repair the startup files, or to run system restore when you can't get into Vista/7.