Tube biasing

[damienks]

I am getting new power tubes for my Peavy XXX, and I am getting them in packs, which are pre-matched (Mesas). The amp has a small bias adjust knob near the 6L6/EL34 selector and I was wondering if I will have to bias the tubes myself? or are they already biased because they're matched? If I do have to bias them how do I do it (Or is there a website that will show me how?)

Thanks very much for any help.