Newbie having trouble compling and running code

Question

Ok I bought a beginning Java book to learn. I loaded the JDK into a file c:\java\jdk1.5.0_06. Set up a folder called code at c:\java\code. Set my paths for both PATH and CLASSPATH under both user variable and system variable to c:\java\jdk1.5.0_06\bin. During compiling I had a problem with the error "'javac' is not recognized as an internal or exter..." I got that worked out. I have my party.class file in the code directory. When I try to run it using "c:\java\code> java party" I get this error. "Exception in thread "main" java.lang.NoClassDefFoundError: party. " I ran a dir and I can see party.class. I get the same results when I run the HelloWorldApp.class also.
One thing I did try was "set CLASSPATH = "
Then I could run the HelloWorldApp.class ., but the Party.class still will not run. It gives this error "Exception in thread "main" java.lang.NoSuchMethodError: main"
I have read through a bunch of forums online but have not find anything to rmemdy this.
Here is the code
Party.java
import java.awt.*;
import java.awt.event.*;
class party {
  public void buildInvite(){
    Frame f = new Frame();
    Label l = new Label ("Party at Tim's");
    Button b = new Button ("You Bet");
    Button c = new Button ("Shoot me");
    Panel p = new Panel();
    p.add(l);
    } //more code here...
} HelloWorldApp.java
* The HelloWorldApp class implements an application that
* simply displays "Hello World!" to the standard output.
class HelloWorldApp {
    public static void main(String[] args) {
        //Display "Hello World!"
        System.out.println("Hello World!");
}Thanks for your help

Answer 1

OK I think I figured out the main method thing. But
now I have gone back to getting the "Exception in
thread "main" java.lang.NoClassDefFoundError: party.
" error. Everything I have read said this was cause
by looking int he wrong dir. But I can run dir and
see party.class
import java.awt.*;
import java.awt.event.*;
class party {
     public void buildInvite(){
          Frame f = new Frame();
          Label l = new Label ("Party at Tim's");
          Button b = new Button ("You Bet");
          Button c = new Button ("Shoot me");
          Panel p = new Panel();
          p.add(l);
     } //more code here...
     public static void main(String[] args) {
              // code here
} Does this one work?