If you need to create a shape or a combination of shapes in any colour, all you have to do is add a shape from the left hand column in the scene editor.

There are 4 basic shapes:

You can resize them and change their proportions by customising:

By changing the values above, you can create numerous shapes beyond just the 4 basic ones. By just changing the tessellation on a cylinder, you can create any polygon you want. Try it for yourself and see what you can create.

You can combine them to create larger shape-combinations or animate them using the animations feature described here.