How about consulting the Excel Help file? Quote:
"By default all cells on a worksheet are locked. Before you protect a
worksheet, you can unlock cells where you want users to enter and change
data, in two ways. To unlock cells for all users, you can use the Protection
tab of the Format Cells dialog box. To unlock cells for specific users, you
can use the Allow Users to Edit Ranges dialog box. Any ranges that you
specify in this dialog box and don't assign a password for are also unlocked
for all users. The cells you leave locked become protected only after you
protect the worksheet."
Cheers,
Joerg