Answers for "sudo nano /etc/wpa_supplicant/wpa_supplicant.conf"

raspberry pi wpa_supplicant

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=US

network={
     ssid="Your network name/SSID"
     psk="Your WPA/WPA2 security key"
     key_mgmt=WPA-PSK
}

raspberry wifi scan

$ sudo iwlist wlan0 scan

raspberry pi scan networks

sudo iwlist wlan0 scan