How to rotate an object with mouse

I am new to Unreal 4 and trying to create a platform shooter for my first game.

I basically want the hand/arm of my character to rotate with mouse to allow aiming with guns. I am having no luck coming up with a solution or finding one online to do such a thing.

Any help with a solution or directing me to where I can figure one out is greatly appreciated.

48078-test.png

I already made tutorial on this Unreal Engine 4 Object Inspection System Part 1 - YouTube
Unreal Engine 4 Object Inspection System Part 2 Final - YouTube