you didn't say whether or not you bought it with a bed and hitch plate or not.
you will find that it is difficult to find a hitch receiver that will bolt onto the dodge frame.
you can not drill or weld to the channel flanges only the vertical surface of the channel and the body builders manual tells you size and set back of holes or your warrantee is voided.
sounds like you have the towing package since you have the controller plug. if you have a bare chassis there is a clump of wires designated for towing at the rear cross channel (there are actually two groups follow the color code on the wires as designated in the manual. they have heat shrink and are sealed to prevent damage.
(you can download all or part of the dodge body builders manual. )
basically what you need are a 7-pin socket and mounting hardware.
a brake controller, and controller harness (i bought the harness from the brake controller mfg) i ordered my controller through
Used RVs, Motorhomes, and Consigned sales - PPL Motor Homes (800-755-4775) they were $200 less for the Prodogy then what it goes for in the stores here.
1. mount brake controller in cab, do not plug in controller harness to the dodge provided socket until you have installed 7-pin socket.
2. connect wires to 7-pin socket and mount socket.
3. now plug in controller.
your in business.
if you need help with the wire designation let me know