2002 Toyota Avalon Head Gasket

Engine Mechanical problem
2002 Toyota Avalon 6 cyl Two Wheel Drive Automatic 200K miles

Hi there,

I think I have a blown head gasket. I put an oil flush through and changed the oil. The old sump oil had a smell of fuel to it. Also, some of the bright red flush liquid ended up in the coolant reservoir. And finally, when idling with the radiator cap off, little bubbles are coming up the radiator.

Being on a pension I am trying to do this as cheap as possible, so my question is:
What is the easiest way to identify which cylinder, it is so I know which head to remove for gasket change?
I realise that this could also mean the head may be warped or cracked.
Where are the spark plugs on the avalon (I am assuming it's the black boxes on the head) and is there anything special that is needed to be done before removing them.
and lastly what is the head bolt loosening order for the avalon engine?

Thankyou in advance.

Andrew