Some things to try:
- Select "tool" by clicking on a button
- Create edges by clicking "Create edge", then dragging a node onto another one
- Add nodes, edges using the "GUI"; remove nodes and edges either using the "GUI" or from the table
- Change color to a color name in the table
- Change color to a hex value (#ff0022) in the table
- Change label, note how it's updated on the vector image
- Change label of a node which is the endpoint of an edge; note how the "from" or "to" field of the edge is updated
- Check out the docco annotated source here