In order to connect your board to wireless you need to have the LINUX IMAGE FOR SD and the wireless card connected to your board.
You can download the SD card Linux image here: https://www-ssl.intel.com/content/www/us/en/do-it-yourself/downloads-and-documentation.html#galileosoftware
You can see how to set up the wireless card here http://www.intel.com/support/galileo/sb/CS-035091.htm
Then, you need to enter the terminal and in the command prompt type the command: ifup wlan0.
If you want to use the Ethernet interface you need to make sure that your board is in the same network as the rest of the network you want to connect to.
You can use the command ifconfig eth0 <ip_address> netmask <netmask_address> up.