Instance of custom blueprint in C++

Hi everyone, Im noob in c++ programming and Im having a lot of problems about how I should declare functions, variables, components… My problem right now is something that seems so easy in other programing languages like c#, Java… What I’m trying to do, is store into a varible an instance of some custom blueprint class that I created previously. This is something that in other languages should be done like:

CustomBlueprintClass instance = new CustomBlueprintClass(params);

Or in blueprints is made (I think) just creating a object variable and choosing the class (image attached)

If someone could help me, I would be very gratefully. Thanks