No worries! We hope you have an easy time getting into Unreal.
Here’s the reference on BP interfaces: https://docs.unrealengine.com/latest/INT/Engine/Blueprints/UserGuide/Types/Interface/UsingInterfaces/index.html
And a youtube tutorial on them: http://www.youtube.com/watch?v=HtB_00h2Ykw
Best of luck!