Open the UE Launcher, select “Marketplace”, download “Content Examples”, then open the UE Editor, and choose the “Content Examples” project. Once it’s open in the editor choose which ever level you want to open, you can then investigate how anything you’re interested in was done by clicking on the relevant object(s) in the scene.
You should probably start with the UE4 tutorials though, this is just simply opening an existing project - if you’re having problems with it you’re going to want to familiarize yourself with the editor, and the tutorials are a good place to start.