wifi.md

Edit /etc/wpa_supplicant/wpa_supplicant.conf

Add WiFi network name and password:

add the following to whatever is already in the file:

country=US

network={
    ssid="testing"
    psk="testingPassword"
}

Run:

sudo /etc/init.d/networking restart

For troubleshooting see: https://www.raspberrypi.org/documentation/configuration/wireless/wireless-cli.md