Follow the instructions above (for creating the table from the Navigator Tree), starting at step 3.
You can also drag the physical table from the Navigator Tree to the Editor Graph canvas to create a new business table based on that physical table.
Another shortcut is to drag the physical table in the Navigator Tree to the Business Tables node in the tree, which will also create a new business table based on that physical table. NOTE that in the M4 milestone, this shortcut is broken... sorry, soon to be fixed!!