Macrium Reflect (easy to find with bing search). It’s a free application for non-commercial use. After you install it, you can image your computer to a network drive, USB external drive, etc. You can also make a bootable CD after you install it to be used to boot from in the case you need to recover. The software can also be scheduled to do backups unattended if it’s something you want (and should) do on a continuing basis. Read the user guide and understand it. The CD is only for booting, you need to keep your actual backups on accessible media. I highly recommend an external USB drive if you do not have a network for such purposes.
...forgot to add... this software will backup everything and IMAGE you PC. This is basically a clone so if you ever lose your hard drive, you can replace it and restore the image without even having to install windows and start over. It will be an EXACT duplicate of the moment in time you last ran the image. If you simply want to backup files that are important, as others mentioned, the built-in windows backup software and an external USB drive are more than capable of meeting that basic need.
I use the Macrium Reflect [free for home use] for my desktop and laptop disk drive images.
Those image programs save HOURS if one ever needs to re-image a drive.
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I also have a 2nd partition on my hard drives and I use those for my data. They usually survive a disk drive crash.
Additionally, USB external drives are too cheap for anyone not use backup their data.
IF YOU CAN’T AFFORD TO LOSE YOUR DATA, YOU CAN’T AFFORD TO NOT HAVE AN EXTERNAL BACKUP.