How to Prevent a Microsoft Excel 2007 File from Opening

1. Open your spreadsheet in Microsoft Excel 2007.
2. Click the top-left 'Office' button, and select 'Save As.'
3. Click the 'Tools' drop-down menu, located to the left of the 'Save' button, and select 'General Options.'
4. Enter a password in the 'Password to open' field, and click 'OK.'
5. Re-type the password in the confirmation window, and click 'OK.'
6. Click 'Save' to secure your spreadsheet.
7. Click 'Yes' in the 'Confirm Save As' dialog windows, which asks if you want to replace the current file. This overwrites the unprotected file with the password-protected version.