How can I start GraphTK?
Use the scripts in your bin folder. In order to start the graphical user interface use the script named Some PC configurations support double-click JAR execution and you can launch the file lib/graphtk-X.Y.jar directly.
What can I do with a generated graph?
Some basic functions for graph analysis are already provided, but the best thing to do is probably displaying the graph with an external tool. Read the manual/help for further information.