All pins are exposed to outside, so you have two options
one is hot air, and the other one is with soldering iron.
if you put very small amount of solder on one pad, and I do mean very small, then place connector on and tack that pin
Now connector should be solid, so you can grab it better, heat that pad again and reheat that pin again, so that connector will seat as low as it can (push it down), that is, if you weren't been able to do that in the first place. Then solder remaining pads/pins.
With hot air you have more options, but again one would be, place small amount on each pad, then place and hold connector in place and melt the solder
Edge of connector must be connected to GND. They are under the connector on each side of ANT pin for that connector