When you run the app, you can see the file browser. You can see a template list to start a project by touching the + button on the top toolbar. From here, select the template you want, enter the project name, and start by pressing the create button. Once you are familiar with the app, you can freely design the app you want with a blank template.
A Scene refers to the unit of screen displayed when you run an iOS app. Multiple Scenes are created for different purposes and are linked together through modals or push to form a single app. Remember that you only need to design on a per-Scene basis.
When you run the project, you can immediately see the Scene list. In the Scene list, you can create a new Scene by clicking the + button and go straight to the Scene editor.
If you go to the Scene editor, you can edit the properties of the Scene through the inspector by clicking the paint icon, so take a look around.
At the top of the Scene editor, if you click the [+] button, you can see various View Objects that can be added to the Scene. You can drag and drop to place it in the desired position on the Scene.
In the Scene list, you can create a Tab Bar Container by clicking the + button. The Tab Bar Container does not edit the design of the Scene like a normal Scene. Instead, it can bundle several Scenes together to serve as the main Navigation. This is a configuration you'll be familiar with as it's commonly seen in iOS. It's generally good to think of this Tab Bar Container as the starting point of the app.
In the Scene editor, you can turn on the Navigation Bar Show Switch when the Scene is selected. If you turn this item on, you can see the Navigation Bar above the Scene, and you can set the Title, color, add action items, etc. all within the inspector. The Tab Bar can adjust the Appearance similar to the Navigation Bar in the inspector of the Tab Bar Container editor.