How to open a Keg of Beer

[laissez-faire]

We bought a whole 50 litre keg of lager. Thing is, it appears to be pressurised. How do we get the beer out in a controlled fashion?

 

[laissez-faire]

You have to knock a tap in and hope it dont **** all over you like it does when most people try it

Pretty sure that is only for ale casks. You can't knock a tap into a steel keg! We need a proper keg tap because it needs to be mixed with gas as the beer comes out. We just need to know where to get the tap!