Doris,
I work with computers often that have issues similar to this and I find that it is very often caused by 'over-clicking'. When the computer is bogged down trying to process something we get impatient and try clicking on other things to do while we are waiting for the first thing to finish or to "hurry" the first thing along.
This never works and usually only makes the problem worse by giving the already overworked or stuck task sequence more events to process. In addition, (and I think this may be what happened to you) sometimes we click the wrong things because the options were still loading when we clicked but before the computer registered the mouse action the list changed.
It is possible to click on an item and set it as your desktop. Any item on the screen or browser can be set this way. To verify, click Start > Control Panel > Change Desktop Background (under the Appearance and Personalization category heading)
From there change the "Picture Location" field to "Windows Desktop Backgrounds" and then pick any of the picture themes shown. Once you have selected a new theme, choose "Save Changes"
This should have replaced your "Head and SHoulders with the selected theme.
If not, then please post the results here so I can try to resolve the issue with you.
Thanks!