Let's make our snowman a little bit more interesting. See the materials library panel at the bottom right corner?
Scroll it down to plastic materials or use the drop down list at the top to filter the list, so it shows just plastics:
Now drag the material you like onto the bottom ball:
Yes, it's that easy. You simply pick a material from the library, then drag it to the object you want to apply it on. You see the changes immediately. Go on and assign other materials to the rest of the objects.
Materials library is a place where you store all the materials that you can ever use. You don't change it when you alter a material in the scene, so it is sort of a read-only thing. When you drag a material onto the shape, it is loaded into the scene and is shown in the scene's materials list:
These materials are stored in the scene and any modifications you made to them are preserved. So by dragging a material from the library, you make a copy of it that is stored in the scene and can be modified.
You can use the materials list to get an idea of how many materials you really have in the scene, which material is assigned to a specific object and so on. You can also select objects by material and assign materials to selected objects there.
There is another panel in Owlet that displays the currently selected material (the one that you select in the materials list). It is shown at the left on the screenshot above. Here you can edit the material, change its color, textures and other properties. We'll not be discussing this now, so all you need to know is that there is a panel where you can see all the materials of the scene and there is another panel where you can edit materials.
As usual, all the changes are displayed immediately.
Great, you now know the difference between the materials library and the scene materials list, you know how to assign materials from the library to scene objects and you have an idea where to look for scene materials and where to edit them.
That's good, let's move on!