excel training courses - Protecting Cells

Cells are protected with a two stage process.

By clicking on format > cells, then navigating to the PROTECTION Tab, you will see a tick box saying locked.

All cells are locked by default, but are only activated once you switch the functionality on.
To do this, click on TOOLS > PROTECTION > PROTECT SHEET.

All cells are locked by default, so your would need to unlock the cells you do not want to protect.