Select the list and press Tab to focus on the drawing area (this will be modified in version 0.0.8).
Then select a router, press "Shift" and move your mouse : the router you chose will move, and each router depending on it will follow it.
After playing for a few minutes with that, you will certainly have something that looks like the picture below.
Select the first router, press "a" and move your
mouse...
That's all, folks !!!