Hi Kaveh!

No need to post to more than one group and be aware that it can take
several minutes for a post to "arrive" at the group.

By default all cells in a worksheet are formatted as locked with the
lock implemented by imposing protection using the Tools Protection
menu.

First select the cells that you want users to have access to.
Format Cells Protection
Remove check from "Locked"
OK

Now:
Tools Protection Protect Sheet
Give and confirm a password (optional)
OK

The user can thereafter enter data in the cells you removed the lock
from but not others.
In passing, I find it good practice to differentiate user access cells
by a different palette color.

But internal Excel protection passwords are easily circumvented, so
only regard this as protection against accidental messing up of
formulas etc.

--
Regards
Norman Harker MVP (Excel)
Sydney, Australia

Excel and Word Function Lists (Classifications, Syntax and Arguments)
available free to good homes.