I am completely new with Navigraph. How can i find out, which AIRAC Cycle is active?
By having a current subscription, you will be using the most up to date AIRAC cycle.
However, if you wanted to actually see what version of AIRAC is the most current, check your SimBrief dashboard. SimBrief - Dispatch
The upper right panel will show you the current cycle that is in effect.
Or you use the document from Eurocontrol 
By the way, welcome to Navigraph 
Cheers
Richard
Another source with effective dates, including currently active cycle:
Regards,
Tim