Hi Sandro, and welcome to the forum. Eugen's advice is good. You'll learn quite a bit from the FAQ document.
There is quite a bit to learn about Lugers. It can be overwhelming, so take your time. While everyone wants to get started with a Luger, sometimes it's best to first do the reading so that you'll understand some of the details that separate a collectible gun from a shooter, and issues related to faking.
http://forum.lugerforum.com/showthread.php?t=13121
__________________

Igitur si vis pacem, para bellum -
- Therefore if you want peace, prepare for war.