not difficult to do, but tricky to re-assemble correctly. Best to find someone familar with lugers to show you how to take apart and put back together. like a gunsmith....
Make sure there are no rounds in the chamber, take the magazine out and take the gun off safe. Then grab something like a pen, small and blunt ( i recomend a click pen). Behing the slide there will...
The owners manual should have basic instructions. If you bought it second hand you can call the manufacturer and they are legally obliged to send you one. If you have access to a computer youtube can...