Except widget, Buildify has some general settings. Here you can find information about them.
Element Tree shows structure of elements, that are currently exist on your page. Read here how you can customize it.
Learn from this tutorial how to make color and font settings for your page.
Read here what can you do with page's elements. There is a number of settings that can be useful for you.
On the Home page at your disposal a list of customizable widgets. You can find them on the right side of the window. With their help, you can create a page with an appropriate design.