boot from USB – Power on the system. – Press and hold the Option (Alt) key on the keyboard when the computer starts. – Select the USB drive as a startup disk when the option appears.
post install go to Software & Update -> Additional Drivers and select your Wireless driver
from terminal check product version: sudo dmidecode -s system-product-name MacBookAir6-2
hold the Fn key while pressing them to get their original functionality(F1-12) to change that : echo options hid_apple fnmode=2 | tee -a /etc/modprobe.d/hid_apple.conf update-initramfs -u -k all