Password Protect An Excel Document

You want to be able to click on your document and for it to ask you for a password.

I am using Microsoft Office Excel 2007

Click on the Office button in the top left, then save as, name the file, then in the bottom right next to save, click on tools, general options, enter the password to open and modify, then ok, then enter the password 2 more times, then click save. If it asks you to convert as xml say no.