The vent unscrews into two pieces. Take it apart, put the face on the front side of the dash and the back of the vent goes behind the dash. Screw it on snug and you're done.
Repeat for the other side
*Because my vents weren't sitting flush, I used my dremel to trim the backside of the vent face a little bit where it was hitting the dash so it would sit flush. Hopefully my goof will prevent other's from having to do so 