Does Shimano 9 speed FD show candence? If so, how do you get it?

No FD I'm aware of measures cadence. Cadence is normally measured with a cycle computer. I'd recommend the Cateye Astrale 8, which you can usually find for around $30.

you mean flight deck, right? the cadence on the flight deck is virtual, which means it is determined by your gearing and speed at the time. to access this option, hold down the button on the right shifter for about 3 seconds, the screen will change and one number will be your speed, the other will be cadence.