Protect workbook in Microsoft Excel 2010
There may be certain instances when you have some sensitive information in your workbook and you want only appropriate or authorize person should see them, it means you need password to keep your workbook safe, this is how it can be done.
Click on File tab and then press SAVE AS button.
Window will open to save your workbook, on left side you save you can see Tool button, click on that Tools button and chose General option
Window will open to ask password and their purpose, that is password to open and password to modify, enter password to open and press ok second window will ask you to confer that password, reenter the password and press ok.
Now then press save to save your protected workbook.