do i need to bleed my rack and pinion?

i have an 89 mustang 5.0 and i removed the rack and pinion to replace the lines on it...i put it back on the car and connected everything and now when the engine is running, the wheel turns back and forth very fast all by itself...i don't know what to do...thank guys and i can't do that cuz of the wheel doing that...i didn't put it on the ground though like you said, is it very important?
 
The rack does need to be bled. It's best done with the front end in the air, and the locks are not hit. Stop just short of them.