Use the mouse wheel for zooming. You can also doubleclick with mouse to zoom in.
Move a map
Drag and drop with mouse.
Save the drawing (all 28 maps)
Once you finished your work, write a fancy name to the input field at the right side and press the "save drawing" button.
If you use a name that is already in use, the original drawing will be overwritten.
You can save half finished work, continue and save the result using the same name again.