STFA - there are a thousand threads on coolant flushes.
But just to add to Kris' comment - yes the most important bleeder is the heater core located just to the right of the battery under the rain catch panel. (Remove rubber strip, pull panel towards front of car to remove.) Your outlet hose will have the bleeder hole (you'll see in the hose a little tiny hole that is surrounded by white) - after unclamping the hose, pull it back (twds front of car) until it is JUST off of the "pipe", of the core, so to speak.
I'm not sure about the 2.8L but my 2.7L also has another bleeder hole in the coolant pipe just to the right and below the TBB in front of the mani. It's a 5mm Hex I believe. Bentley states there is another bleeder on the return line just under the expansion tank on the 2.8's. This one is to be bled before the one by the TBB. (Go in order - Heater Core --> Reservoir Return Line --> TBB). My 2.7 doesn't have the return line/inlet one, or at least I never found it - so what I do is just d/c the inlet hose from the tank until I get a steady flow of coolant, then reconnect inlet to tank. I strongly suggest doing a better STFA or buying a bentley repair manual before attempting another job like this without proper instructions though...
Hope this helps!