Draw a list of available stages on screen, have the player cycle through it and and change scenes as they select one of them.Alternatively, create one actor that the player can click or whatever input method your game uses, and use instant customization for each one you place on your stage select scene, each leading to different a scene.
Here is my video on behaviors, and it mentions instance customization: https://youtu.be/SaI5-TmRhOMThis should be enough so you can go with the actor type route I mentiond. If you want the list option, read about lists and attributes on Stencylpedia.