Everything you see on the program is a scene: a stack of layers on the 16:9 canvas (the vertical canvas has its own — see Outputs).
The + menu in the Layers panel is the one place to add anything:
Drag to move, handles to resize, and hold the rotation handle for angle. Double-click a name to rename. The inspector (right side) collapses when nothing is selected — pin it open with the pin icon, and drag its edge to resize.
Per-layer controls include:
Save the current canvas from the Scenes drawer (camera button). Scene thumbnails render live. Loading a scene stages it to preview in studio mode, or applies it directly when studio mode is off. Scenes can also carry an embedded vertical arrangement so one TAKE lands correctly on both canvases.
Sources that aren't visible anywhere auto-park — they stop consuming capture and GPU until needed, so a big library costs nothing while idle.