Best Answer - Chosen by Voters

What browser are you using? I'll give the instructions for the most common ones;

Internet Explorer 5,6, &7:
1. Start Internet Explorer.
2. On the Tools menu, click Internet Options.
3. Click the General tab.
4. In the Address box, type http://www.facebook.com
NOTE: If you want the page that you are currently viewing in Internet Explorer to be your home page, click Use Current.
5. Click OK.

In firefox:

Click on TOOLS on the menu bar at the top of the Firefox screen, then click on OPTIONS

After clicking options you will see the Firefox Options dialogue box.
Type the address of the webpage that you would like to use as your new homepage into the box providedand click the OK button.

If it is the webpage you are currently viewing just click the Use Current Page button then simply click on the OK button.