How to password protect a document file

In ms office 2007, click the office button and select save as.
The save as dialog box appears.In the save as dialog box you will be able to see a tools button . click it and select general options.If you want other persons to enter a password before they can view the document, type a password in the password to open text box.

Here after only the people who possess the password will be able to view the document.If you want some one to view the document but not allow every one to save it then you can use the password in the password to modify text box.