From Java Tutorial - Summer 1997 Part 1:Introduction to Java Language CEWES Tutorial, Classes SU/Jackson State -- July 22-25 and Fall 97. byNancy J. McCracken,Geoffrey C. Fox
You should name the file with your applet name, HelloWorldApplet.java, run the compiler (javac), getting a bytecode file HelloWorldApplet.class, which you put in a web directory.