I made my main menu with all of its UI, and used a separate actor with only a camera to create the background- that way I can make a realtime background. And when i click play nothing happens at all! Please help!
We need more detail to be able to help you. Can you provide a video showing the Blueprints and UI widgets? If you cant do video, at least post screenshots of the blueprints and UI.
This is likely due to not understanding how input, player controlled characters, and spawning UI elements work correctly.
Here’s the tutorial on creating a basic main menu from the docs. It doesn’t quite teach what you want (it uses a static background instead of a 3D one) but you should be able to modify it to your needs. The concepts it teaches include changing the player pawn over to something that won’t move around, summoning UI widgets, and accepting input.