Lisa,
Give this a try:
Select all the cells that you want the user to be able to change.
In my case, cells A4 & B4. Select the cells and "Format", and the
"Protection" tab.
"Unlock" the protection on the cells.
Then select "Tools", "Protection","Protect Sheet".
Pick a password that you will be able to remember. Select "OK".
Then re-enter the password.
Save and have fun.
You might want to practice on an unimoprtant worksheet first.
hth