After installing Firefox 3.0 you must have noticed that the Back and forward button from the toolbar is missing. Do not worry, no need to re-install firefox, you have downloaded the right version. The button can be configured easily and can be restored back e. You can also embed stumbleupon, print and many other buttons easily.
Right click on the area where you want to enable the button. Select customize, a customize toolbar window will get open. Then find the button you are looking for just drag and drop to the desired place. You are done.Now you should be able to view your desired button on the toolbar.
Firefox should have placed back and forward button as a mandatory feature and not as an optional component on the standard toolbar. Do not understand why Firefox did that.