We will design develop Project 2 (Phase1, Phase 2, and Phase3) for the rest of the semester. You Project 2-Phase 1 due on 10/30 should have a complete (i) requirement analysis (use case diagram) (ii) design of the software (class diagram) (iii) data structures, class definition, algorithms and Java code for the model of Scotland Yard game. This involves extensive thinking, expressing your thoughts using UML tools, designing solutions and lot of  coding and testing. This phase will have complete logic implemented but no GUI. No extensive GUI is needed in this phase. Plan to learn some more Swing (in addition to Project 1) during this phase so that you may use it in the Phase 2.

2. Need a skeleton including a softmap of the ScotlandYard game?

Look at skelton posted at: http://www.cse.buffalo.edu/~crahen/cse116/project2

3. How do get the data about the locations into the program?

You can initialize the locations/routes using static initialization or hardcoding. Also for testing purposes you may start off with just a few routes/locations, say 20.

4.  Can I use a graphic tester for the model?

Yes you may.

5. I have the class diagram ready. But I don't how to proceed further.

Consider one class at a time, define its data structures and methods, implement the methods, test the methods. Move on to the next class. Then test the interaction among the classes.
Write the main control loop and test the integrated project.