You won't install JBoss in Netbeans, but you may setup the JBoss as Application Server for your IDE Netbeans. They are two softwares, you should have installed them separately together with the JDK mentioned in the link you given.
but I haven't understood nothing.
? do you know what you are saying ?
The question is:
HOW I CAN INSTALL JBOSS IN NETBEANS?
I've downloaded JBoss zip archive, and i've unzipped it in a folder.
Now when i choose tha installation folder of JBoss in Netbeans for installing new server, Netbeans tells me that the path doen't contains a valid JBoss installation.
How i can solve?
Ok, I don't know how to install JBoss Application Server in Netbeans, but i know how to setup.
1) Tool > Server Manager
2) Add Server
3) Server: JBoss Application Server 4
4) Installation location: C:\jboss-4.0.4.GA
5) Then you should able to select the server instance, port, etc.
I have tested in Netbeans 5.5 Beta 2, JBoss Application Server 4.0.4.GA.
Check version of your Netbeans, JBoss App Server.