How to backup files:
Open File Explorer from the Taskbar > Go to the file/s you wish to save > right click on it > hover Mouse Cursor over Send to > select an external Hard Drive or Memory Stick that you have plugged in to save them to.
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"Set up a drive for File History and Restore files or folders using File History"
http://windows.microsoft.com/en-us/windows-8/set-drive-file-history
"Introducing Windows 8.1: How to Backup Data with File History"
http://www.7tutorials.com/introducing-windows-8-how-backup-data-file-history
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Use System Image Backup
You can still use System Image Backup in Windows 8/8.1.
I personally don't use it as there are often problems with it when Restoring an Image.
"System Image Backup in Windows 8.1"
https://www.winhelp.us/system-image-backup-in-windows-8-1.html
"Windows 8.1 Tip: Use System Image Backup"
http://winsupersite.com/windows-8/windows-81-tip-use-system-image-backup
"Restore a System Image in Windows 7 and 8/8.1"
https://www.winhelp.us/restore-a-system-image-in-windows-7.html#reimage
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These are quite good programs to use for Complete PC Backup and are free:
"EaseUS Todo Backup Free"
http://www.todo-backup.com/products/home/free-backup-software.htm
"Welcome to EaseUS Todo Backup Manual"
http://www.todo-backup.com/support/help/
http://www.todo-backup.com/download/docs/User_Guide.pdf
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"Macrium Reflect Free"
http://www.macrium.com/reflectfree.aspx
"Macrium Reflect Tutorial"
https://reflect.macrium.com/webtutorial/tutorial.asp
Cheers.