1) Download and install
macrium reflect free (click) (current version: 7.2.3858).
2) Get a
rewritable CD.
3) Open macrium and click
Create bootable rescue media (and follow the instructions to create it one).
4) Test the bootable media (if it boots your PC and open the macrium reflect program in a non-windows environment, i.e. it should not open/start your windows 10 OS)
5) Reboot and create a
system image.
I.e., without your important data, if you have "backupped" them in another location.
You can also create a full system image, if you prefer, but you'll need more space available.
The windows images created should be put in another disk, and shouldn't be put in your ONLINE disks (i.e., they shouldn't stay in your machine).
As example, I usually backup the first 5 partitions, because the last one is only for data (I put there software, games, browsers, temporary internet files, etc).