Harry, There have been a lot of conversations about this, including code samples and links, in the last couple weeks.
Use the search tool for both the Servlet and JSP forums with keywords like "servlet applet" and you should find plenty of information.
If you're stuck with a specific error and want help, take some time to put all the relevant information together before posting. Include OS, Server version, Java Version, stack traces, code snippets. The more information we have, the easier it will be for us to help you.