See how to use a cleaning rod tool on a Luger P08 (also known as Pistol Parabellum). See the tips to cleaning the barrel receiver assembly.
Be sure to follow all disassembly and assembly instruction found in the technical section of http://www.lugerforum.com.
If you are not sure of what you are doing or if the gun is not working properly, take it to a competent gunsmith.
Be sure to follow all NRA firearms safety recommendations.