f-stop display

Hello,
I'd like to know how to show the f-stop display on the camera? I have a Canon 17-55 f2.8 and Tokina 11-16 f2.8.
I'd like to know how to show the f-stop display on the camera? I have a Canon 17-55 f2.8 and Tokina 11-16 f2.8.