How to write a Java applet

• Download and install the Java Development Kit (http://java.sun.com/j2se/) for your operating system.
• Write and compile a class (or set of classes) that extends java.applet.JApplet
• Write an HTML file that has an <applet code="[your classes's name].class" height="[height]" width="[width]"></applet> tag in it.
• Use "appletviewer [your html document's name]" to view the file. appletviewer is one of the executables included in the Java Development Kit. Or, if you want to, you can use any other Java-compatable web browser (almost all modern browsers) and enter the html document.

There is a lot more information about writing applets in Sun Microsystem's documentation (http://java.sun.com/docs/books/tutorial/applet/index) on this topic.