It may all depend on how you have IE9 set up and displayed at present, but ....
On the right-hand side of your screen you may see a couple of >> arrows. To the left of those >>s, you may well see the word Tools with a downward pointing arrow.
Click on Tools there and then drag down until you find Toolbars with yet another > arrow.
From there, drag down to Customize , and then on the left will appear all the buttons that you can then add to your toolbar.