This is the Netbeans Java Developer IDE AND the JDK for developing Java
apps.

The JDK5 should also be on your system say "C:\Program
Files\jdk1.5.0_04". This is what you need to develop Java applications.

Netbeans is a Java developer IDE. You should see a Netbeans icon on your
desktop. Just double click on that to bring up the Netbeans IDE.

Or select  Start \ NetBeans 4.1 \ NetBeans IDE

If you do not see the icon then just goto your Netbeans subdirectory and
double click on "C:\Program Files\netbeans-4.1\bin\netbeans.exe"

Now that the Netbeans is open you will need to learn this IDE. You can
play with the samples off the welcome screen.

You can use any number of Java developer IDE's out on the Internet that
are also free.

If you have never developed Java code before I would recommend a easier
IDE like JGRASP http://www.eng.auburn.edu/grasp/ or BlueJ
http://www.bluej.org/

Yes.
Netbeans and the JDK provide everything you need to write and execute
Java programs. In fact the JDK alone is all you need to write and
execute Java programs, Netbeans just provides a sophisticated GUI
environment that helps with more complex projects.

Before you jump into Netbeans, however, I suggest you start with the
very basics.

Get yourself a basic book on Java or choose one of the web based
tutorials like http://www.iut-info.univ-lille1.fr/docs/tutorial/

Practice by writing some very basic Java programs using only a text
editor and the JDK. Once you understand how this works you will learn to
use Netbeans far more easily.

For example, here is how to do "Hello World" using only the JDK:

1) Using your favourite text editor (Notepad, Emacs, vi etc) create a
file called "hello.java".

2) Enter the following in the file:

class hello {
    public static void main(String [] args){
        System.out.println("Hello World");
    }
}

3) Save the file

4) At a console command line type:
javac hello.java

5) Step 4 caused the Java compiler to create a file called "hello.class"

6) At the command line type:
java hello

7) Step 6 caused the Java Runtime to load java.class and execute it.
Note that you did not type "java hello.class" or "java hello.java" to
run the program. You just typed "java hello".

8) If you are lucky you should see the words "Hello World" appear on the
console.

The Java compiler (javac) and the Java Runtime (java) are both included
in the Java Developers Kit (JDK). While you can use only the JDK for
Java programming, for any serious development you need a GUI based
development environment, like Netbeans.

Trying to use Netbeans without learning a few simple things with the JDK
first is like trying to solve a Integral Calculus problem without
learning arithmetic first.

BTW I use Netbeans as my development environment.
I'm very happy with it.

Oh yes, you will be much happier if you download the documentation that
goes with the JDK too. Last time I looked it was a separate download.
Once downloaded and installed it the documentation becomes available to
Netbeans and this helps immensely. Netbeans will prompt you with
function parameters and descriptions if it has access to the
documentation.

I agree with the others - leave off the IDE untill after you/(your son)
have Java in the bag.
There's quite a learning curve just learning the IDE - whether its Netbeans
or Eclipse - or some other.