it depends what kind of pump it is
many pumps have a latch or this switch that u have to flip and start putting air into into it, once ure done flip the switch back and take the needle out soon because the air is being released
here's what it looks like
do u see the red switch it has, on the part on the floor ?
http://www.cyclestore.co.uk/images/products/large/6453.jpg