How to back up your computer with Windows 7. Create a system repair disk & backing up your files to a external hard drive.
This is the part you need your blank CD.
Without a system Repair disk, if your computer has a major malfunction (i.e. Hard drive fails) then you may not be able to restore your computer to full functionality. You may be able to use your windows disk instead of a System Repair Disk, although not all computers come with a disk (thanks Microsoft), so we strongly recommend that everyone create a System repair disk. It only needs to be done once!
a) Open > Windows Button
> Control Panel

From Control Panel
Open > System and Security (top green link)

From System and Security
Open > Backup and restore (6th green link)

From Backup and Restore
Click > Create a system repair disc (4th link on left hand side of screen)

Insert your blank CD into the drive, then click “Create Disc”

Once the disk is complete, press OK, eject your disc, and label it as directed on screen. E.g. “System Repair Disk Window 7 64bit”
From Control Panel
Open > System and Security (top green link)

From System and Security
Open > Backup and Restore (6th green link)

From Backup and Restore
Plug in your external hard drive into the power and also into the USB port of your computer.
Click > Backup now
Select the source as your external hard drive.
Press OK
Screen snap shot of backup in progress:

Windows will automatically schedule a back up for you, try to have your external hard drive plugged in at this time, otherwise for future back ups, follow step 2 to run a manual back up. You should back up your computer every month at least.