It's really easy, and working on modern Stihls is quite intuitive.
Basically on what Snowdog posted, but your first order of business is to empty the gas out, then remove the handlebar. Then you pop out the white annular buffer plugs, and remove the self-tapping screws in the annular buffers. Then like Rick said, you can take out the throttle linkage, carb adjustment screws grommet, carb, intake sleeve (goes behind the carb in the intake boot). Then you can push the intake boot out of the airbox carefully. There's a buffer on the high side of the flywheel side of the case that you'll need to take the self-tapping screw out of also. Then you can remove the starter and un-hook the kill switch wires from the ignition module. You'll probably need a dental pick or something sharp to remove the wire that hooks directly to the module.
Once you thread the wires out you can carefully start working the tank off. Once you get the tank backed out about an inch, you'll have room to un-hook the impulse hose. After that it's obvious.