The first thing to do is work out what the crash was.
The second to do is read the list of places the crash has occured. In all but the simplest of programs, there's going to be more than one line number. If a method is being called, then the line number of the call, and the line number in the method where it crashed will both be given. If you have crashed a Swing application, then most likely the error will show many Swing line numbers. You should usually ignore those, and find the lines in your code where it went wrong.