psasu
Depending on what you actually mean by backing up?
But if it's just a case of saving the latest information you have created (updating) then name your file, save to the external drive using your browser, the next time you need to backup (a day or week later, whatever) name the file with the same name then when you save it it will tell you that a file by that name already exists and do you wish to overwrite the file (replace it) yes to all.
This will give you a new backup each time.
As I said, it really depends on what you mean by backup.
Martin
Start by questioning and soon you will be answering.
So please take but remember to return and give when you can.