PLEASE HELP!! Need help programming arm??

[amirjpl]

Thanks for replying guys,
Can someone explain the PID loop in depth, and show an example or something that can help me get started.

Just some more information about the arm.
It will have an encoder, since the encoder gives back feed back can't that be just used to keep the arm at a preset constant speed??

Or is this something that PID has taken into consideration.
The help has been great so far, please keep it coming.