Add Text to the Shape
The Text Box
option looks like a flag:

There are two Text Box options. The
one in the Group (the blue box of Shapes) creates a NEW Text Box. The
one outside of the Group adds text to a shape.
2. Format the Shape (Add Text)
Click on the shape.
You should see the Drawing Tools.
Go to the Format Ribbon.
Go to the Shapes menu.
Choose a Shape.
Hold you cursor on a blank place in your document and
drag a small square. You should see a shape that you can select, format
and resize.