How to Protect a Workbook in Excel 2007
At times, you may want to control who is able to view and edit an Excel 2007 worksheet. This may be due to the sensitive nature of its content, or perhaps the content is original and you do not want it replicated. One of the easiest ways to accomplish this is to password protect the worksheet, a process that is incorporated into saving the file.
Launch Excel and open the file that you want to protect with a password. Click the "Office" icon button in the top-left corner of the interface. Click "Save As" and then scroll over and click "Excel Workbook."
Click the arrow to the right of the "Save in" drop-down menu to choose a location on your system for the worksheet. Type a name for the file in the "File Name" field.
Click the "Tools" button in the lower-left corner of the window. Choose "General Options."
Type passwords in the "Password to open" and "Password to modify" fields. Click the "OK" button. Click the "Save" button.