Casting to Hud

So if I cast to a Hud blueprint I made, where do I specify the object? Like how do I find that hud?

When you cast to your hud it will give you an output pin that is a reference to your hud. You can promote that pin to a variable to be saved and used for later. It will be located under variables section.
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You define your HUD class on the GameMode or GameModeBase. You can get the HUD from the PlayerController.

I’m looking for what to put in under the input pin for object, I can’t find the Hub I have created.

Make a GetPlayerController and from that GetHUD. To get the specific type you created it has to be defined in Project Settings->Maps and Modes->DefaultModes expand “Selected GameMode” and there you have “HUD class”.