Hi Chrissy
By default, all of Excel's cells are Locked, but that doesn't become
operative until you apply Protection to the sheet.
So, mark the range of cells you wish to allow alteration and
Format>Cells>Protection> remove the check mark for Locked.
Then Tools>Protection>Protect Sheet> optional whether you use a password
or not, but be sure to remember it if you do give one.

Please note, even with a password, it is not totally secure, as there
are plenty of password removal algorithm's freely available on the web
which will allow the user still gain access to the cells if they are
determined.

Hi,

Tools -> Protection -> Allow Users To Edit Ranges -> New

Select the cells you want the users to be able to edit and click
Protect Sheet.

Regards
Martin

Hi

By default, Excel's cells are all locked - but remain in use until the
worksheet is protected.
Select the cells you want to use and go to Format/Cells and click on the
last tab, Protection. Uncheck the Locked option. Now you can protect the
sheet by going to Tools/Protection . . Protect Sheet.

Hope this helps.
Andy.