Steps1 - take off the valve core cap
Check the valve core.
Check air pressure with the pressure gauge.
check to see how much air there is. Should be anywhere from 15 - 17 psi if more or less you need to adjust it.
to add air just push the air hose nossel on and keep it there few a moment and check it again.
Put the valve core cap back on it.
And now you know how to check air pressure in a tire like a pro.