How to make word document read only

This thing is for office 2007 and for other version you can go and change the properties to make it read only.
1. To make a document read only, click on the office button on the top left corner and select Prepare.
2. Inside prepare menu, you will be able to see the option, Mark as Final.
3. Once you select the option, you get a pop up confirming that the document will be saved and made read only.
4. Once the document is made final, you get a message that status property is set to final and typing and editing commands are turned off.
5. Now you open document . It is read only.