It only goes down. You have to piece the parts together but let me see if I can find a post that has some pictures and info. Unfortunately I didn't take any. Should have and done a write up on it.
I originally had it set up with a PAC TR7 universal trigger module so I could use a keyfob to drop it (3 press's of the door unlock would open the tailgate) However, because the newer truck's use a PWM 12v signal it was not consistent in interpreting the clicks and didn't work all the time or would drop it after 1 press so had to disconnect it. That was really neat when it worked.
This is the actuator I used. Basically you attach this to the rods that come off the tailgate handle on the inside. Wire it to a relay and switch, when you press the button the actuator pushes the rod and opens the tail gate. Also have a Dezee? hydraulic tailgate assist so it doesn't slam down.
https://www.amazon.com/gp/product/B0009SWLE6/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1