Menu / Shelf
You can find rectangular buttons with icons on the sides of the shelf. The buttons represent different packs of objects and tools. If you press on one of them it will be opened with multiple objects spawned on the top of the shelf. To get an object—just grab it out of and place on a scene.
You can import your own 3D models, images, sounds, and videos. To import, find your project folder: .../Documents/Tvori/Stuff/ on Windows and put your files there. Then go to Tvori, open the shelf and press Import button to find your files there on the top of the shelf.