Howdy,
There is a page dedicated to Blueprint Interfaces here:
https://docs.unrealengine.com/latest/INT/Engine/Blueprints/UserGuide/Types/Interface/index.html
As well as Direct Communication here:
https://docs.unrealengine.com/latest/INT/Engine/Blueprints/UserGuide/BlueprintComms/index.html
Hopefully these will point you in the right direction.
-W