Help:Authors/including Java applets

First, upload the archive of the applet (.jar file) using the Special:Upload link (found at the bottom left menu). Then, include the following code into your article

<java_applet code="name.class"  height="number" width="number" archive="name.jar"></java_applet>

For example, the code

<java_applet code="MandelbrotSet.class"  height="350" width="300" archive="MandelbrotSet.jar"></java_applet>

produces

You need to be a curator to upload .jar files.