Step1
The first step is to figure out where you will be backing up the computer to. You need an external hard drive with enough space to store a full backup. To determine how much space you need on a Windows PC, go to My Computer, right-click the drive, and click on "Properties". From there, click on the "General" tab, and look at the size of the drive. If there are multiple drives on the computer, figure out the total size of all the hard drives. Buy an external (USB) hard drive that's at least twice the size of your computer's hard drives.Step2
Once you have the hard drive, you must acquire backup software. There are several options available, like Norton Ghost and Macrium Reflect. Each piece of software is similar, but Macrium Reflect has a free edition, which will be used for this article. A download link is in the "Resources" section, located near the bottom of the page. Follow the instructions on screen to install the software.Step3
Plug in the USB drive, following the manufacturer's instructions, and then load the backup software. Once you have the software loaded, you must create a new backup. In Macrium Reflect Free Edition, click on the "Create a backup image of an entire disk or selected partition(s)" button. Read the instructions on screen and select the disks to backup. You will need to select the backup location as well; make sure you select the USB hard drive!Step4
Run the backup. The backup will take a long time, depending on the size of the hard drive. Once the whole backup has been completed, exit the backup program. 
