cat /sys/class/net/wlan0/address

Is one way to get the MAC address in a terminal, BUT if you do not see wlan0 when you run ifconfig this method won’t work either as the interface isn’t configured/recognized.

You need to add an SSID and passkey to sudo nano /etc/wpa_supplicant/wpa_supplicant.conf and then run sudo ifup wlan0

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