The below documentation should be applicable for at least FreeBSD 11 (and 10 except for maybe the sysctl command):
To find out your wireless device identifier run:
sysctl net.wlan.devices
To create a secure network configuration file run (replace myssid and mypassword with that of your router's ssid and applicable password):
wpa_passphrase myssid mypassword > /etc/wpa_supplicant.conf
To create wlan0 device in which to connect run (replace urtw0 with the output from above sysctl command relative to your wireless device identifier):
ifconfig wlan create wlandev urtw0
To connect to the wifi access point:
wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf
Then to actually get an IP address run:
dhclient wlan0
If this fails disable the encryption on your router and verify the card can connect without encryption. If you need further assistance on doing this (such as what command to use to connect without encryption) contact support.