I would think you could get a manual from Steyr or Dynamit Noble (they are the importer as I remember).
However, I owned one and can help you with your question.
On the opposite side from what you show in the picture, there is a button with 2 holes in it (and you may have a set of keys, you can push it down and rotate it to lock the weapon), push that button in and flip the lever next to it downward (make sure the weapon is empty and the striker is not cocked, you will have to dry fire this weapon to disassemble it, it will not hurt the weapon, the manual instructs you to do so). The slide will then slide right off the front of the frame (like a beretta 92, 9000s, etc). The recoil spring is captive (no worries about it launching across the room), just lift it out of position, and remove the barrel. To assemble, do the reverse (there is a small step for the recoil spring to sit on the barrel lug (like a beretta 92), do not just shove it down to the barrel, it sits on the edge. Run the slide back onto the frame and the release lever should reset into position (or flip it by hand).
That's all there is to do.
Have fun, that's a great pistol.