The document window is the main window which contains the database structure. The database structure is drawn inside a scrollable area called the canvas. It can be scrolled using the scroll bars at the right and bottom. You can also scroll by holding down the Option key and draggig the canvas around

You can have more than one document window open at once. To switch between different windows either click on the window you want or use the window menu to choose a different window.

To select an object click on it. To move an object drag the title bar of the object.