By default, JRaceman uses a built-in username of "jraceman" and password of "jraceman". For single-user systems and trusted networks, this is usually acceptable. For increased security, particularly when running a JRaceman database server, you can specify another user and password. To do so, use the -user and the -password options the first time you run JRaceman for a new database:
java -jar jraceman.jar -db database -user username -password password
After this, when running a client (or when running in single-user mode), you can either specify the user (and optionally the password) on the command line in the same manner, or you can simply start JRaceman and fill in the user name and password when it presents you with the dialog for that purpose.