whats the best way to bleed the system. think i have a air lock. got a new stat and cap.

does anybody have a diagram of the way the system works.

 

Best way to bleed it is easy, leave the cap on the car with the water level normal, go for a drive, stop, top up if necessary the next morning.
The other name for the expansion tank is the de-gas tank, the gas being any air in the cooling system, the action of the super heated water in the engine after shut down whne it gets a LOT hotter dispels the air into the tank, and you will see the level drop some 10 minutes or so after shut off, if you don't want to watch it leave bonnet closed as keep the heat in.
This is assuming it has a nice clear turbo return pipe, as this is the highest point it acts as the de gas pipe.
Leaving the cap off takes away the pressure which helps the de gas prcocess, so always keep cap nice and tight.
tabetha