Thanks to Josh’s guidance, I want also to share my today’s accomplishment, my first custom blueprint node ever 
I want to use Blueprints as much as possible and even for a complete C++ novice like me was simple to create a link between Steam API and Blueprints:
http://i1234.photobucket.com/albums/ff408/BrUnOXaVIeR/UE4FirstBP_zpsdc439cda.jpg~original