New to java but willing to learn.

I discovered an excellent Scrabble game done in java called Jabble (http://domcobley.50megs.com/jabble.html)

It works really well but I would like to make a couple of tweaks to it (i.e. make it 800 x 600 on startup without having to resize and changing some of the colours).

So, I decomplied the jar file, made some changes and used NetBean 6.8 to do a clean and build but I get a lot of errors which I don't understand.

I would really appreciate if somone could tell me if they can rebuild the jar or am I wasting my time as the jar file was built in 2001? If someone can rebuild it can you tell me how it is done?

Much appreciated