The Oooh Fishal gasket is a metal crush washer thing that fits inside the head. The clamp pushes the header in and crush seals the gap. Nothing should be a gasket like you would expect to see between a water pump and block. You may not have gotten it out yet. They are tough and can be reused unless it's damaged.
Don't get strong tightening the thing up. Much better to snug it every few months than bust something off.
1/4" ratchet held thumb on the head, close fingers gently, feel the clamping force,
Antisieze is your friend.

At the place where the header bolts to the head - there is a round gasket that fits into a recess in the head.  Once it is installed and the bike is run, the gasket conforms to the shape of the exhaust port and it doesn't fall out, and looks like it is part of the head.  It deforms and squishes a bit when first installed, and that causes it to get stuck in the head.  This gasket is what the flange on the pipe seats against - the flange with the 2 holes in it should not seat against the head - there should be a small gap.

You should be using anti-sieze on the 2 bolts that hold the pipe to the head - as they can get stuck and that is a big problem.  You should also not tighten them too much - I use a 1/4" ratchet and one hand to snug them in place.