You should set it to point to an actor in the engine or from another code if you are pointing to an actor. Drag and drop an instance of your actor into your preferred level and under your script menus, you’ll see some drop menus that will show actors to you. From there, select your preferred actor.
If you’ve made a BP instance out of your class and you’re trying to set the pointer using BP nodes, you should set the actor’s UPROPERTY to BlueprintReadWrite. The , you’ll be able to say Set BackAndForthActor and then you’ll be able to set your pointer up.