after that we captured the wpa2 handshake (if you don't know how just search within the site) we can crack it with a password brutforce (if the password is in our wordlist). also we need and word list of all the posible passwords

aircrack-ng capturedwpa2.cap -w /the/directory/ofthe/passwordlist.txt

file.cap for the file containing the captured wpa2 handshake and -w for the wordlist