Hi Bright,
Could you please make sure to create a description and summary separate; we’ve noticed you tend to make very long summaries instead. As far as what you are asking, it depends entirely on what you want to do. Your question is rather vague, could you please give a more specific example? Here is some documentation on blueprints in general that may put you on the right path:
https://rocket.unrealengine.com/docs/ue4/INT/Gameplay/Blueprints/index.html
Thanks,
Alexander