Anyone know anything about boilers?

There should be two taps under the boiler somewhere, open them up, let the water run through the system and close them back off again. I don't really understand why, it just works on mine.

isn't that venting the system? If the boiler is full of air you turn a tap till water comes out of it?

there is a tap on the side, when i turn it water flows through it straight away. Maybe I should let it run for a while?