I would also suggest that you give them their own User Accounts with limited privileges. That way they won't be able to undo the good work you will have done.
BTW, all this info is on your own Hard disk, of course, and can be found from Help and Support.
You may not find the Sharing tab when you right click on Properties. This will be because you have a tick in the box for "Use Simple File Sharing(Recommended)" in the Tools>Folder Options>View page of Windows Explorer.