In order to use the built-in System Image tool to create a disk image in Windows 10 do the following.
1. Press Windows key+I.
2. Select "Update And Security" and press Enter.
3. Select "Backup" and press Enter.
4. Tab to "Go To Backup And Restore (Windows 7)" and press Enter.
5. Tab to "Create a system image" and press Enter.
6. Make sure that the "On a hard disk" radio button is selected.
7. In the "Selected Hard Disk" combo box, choose the drive on which you want to store the image.
8. Select the "Next" button.
9. A list of drives and partitions which you can backup to the image will be displayed. Your C drive should be checked/selected by default, but if it is not you can press the Spacebar to check it.
10. Select the "Next" button.
11. A list showing which drives will be backed up is displayed. Select the "Start backup" button to create the image.
12. When the backup is complete, you will be asked to create a repair disk which you only need to do once, then select the "Close" button.
Note that restoring the image will require sighted assistance.