After watching the video, I suggest getting acquainted with the basics of the Spline interface: its main panels, controls, and menus to be ready for the upcoming lessons.
Now you know that the Spline project interface consists of:
The area where you work with your objects. By default, you look at the scene through the "personal camera."
The left panel is the place where you can manage your objects. For example, you can select objects and search for other ones. You can also create and switch scenes. Remember, you can have up to 3 scenes in a free version.
The right panel is available when there are no selected objects. From this panel, you can change the "Viewport" and "Play" camera. Additionally, you can manage global light and shadows. Turn on physics, visual effects, fog, helpers, and grid.
Also, you can find all project assets, such as images, saved materials, colours, etc.
When an object is selected, the right panel switches to the object panel, where you can manage the object by changing its: