To get started solving real hacking challenges you want to dive into the world of the Hacking-Lab.
The Hacking-Lab LiveCD is a full fledged pre-configured OVA appliance for Vmware or VirtualBox based on Debian Live with Kali support. It will give you a jump start in accessing the Hacking-Lab-Universe and it is free.
Please find here some tips&tricks if you should experience any problems with the setup of the Hacking-Lab LiveCD. This information was just extracted from a test run with 40 pupils at the Hochschule Rapperswil (HSR).
Stay tuned for more information about this years conference and watch out for news about the Cyber Security Challenges!