Looks like a cool event, Ragnar!
I have a lot of other things going on at the moment, or I would probably sign up myself!
And on the AP:
Top right you set the course you want to fly (upper ring with degrees markers will move)
The lower ring is your heading indicator, which can be adjusted with the knob in the middle, underneath it. Press "D" if you accidentally turned that one, to reset it to the correct current heading.
Make sure you are flying level (v/s indicator)
Bottom left flip the switch from AUS (off) to EIN (on) and a green light will pop on. you're on Autopilot now
A word of warning, though:
The AP was originally only developed to assist in bombing accuracy, so it will only hold your specified heading AND PITCH. The latter is important to keep an eye on when engaging the AP, if you do not want to fly into terrain
