Plug The External Drive in and Clear it, I have to admit that I formatted it first time around.
Start Button > Control Panel > System & Security > Back-up your Computer > It will now walk you through the setting up of the back-up > chose your External Drive and tell it to go ahead. When it's done, open the External Drive and there will be 3 files on it which do not appear to be large enough but if you look at the Drive's Properties, you will see that there is a considerable quantity of space taken up.
All you need to do now is to make sure that they are both turned on between about 6pm and 9pm on each Sunday. You will notice the one of the Files Date has changed. You can change the back-up time and date to suit you.
I have never tried a System Restore, from my Back-up, and hope never to have to but will work my way slowly through the instructions.