I think you have the wrong file for your needs. So this zip who ends with src suffix means that this is the source code. It is nessecary if you want to make changes to the original version. It is more for IT experts.
You need the other one. Inside the zip file there is install manual. It is for advanced end users but I think that if you follow the steps you can make it.
In the install manual is said that you can choose between JBoss 4.0.5 and JBoss 4.2.x. Better choose the second one 4.2.x.
currently I am using the forums of sourceforge for the project it is temporary. But you can help me add some life to this forum if you post your questions here:
http://sourceforge.net/forum/forum.php?forum_id=723094