Steps for Java Web Start

1. Make jar file of your class files and resources like icons, images etc. using following command:

   jar cf JarFileToCreate.jar abc.class def.class ...

   For More details on creating Jar files, see create-jar-file-for-java-app
2. Make jnlp extension text file with following information:

   <?xml version="1.0" encoding="UTF-8"?>
   <jnlp spec="1.0+" codebase="http://localhost/jnlp" href="MyApp.jnlp">
       <information>
           <title>My App Title</title>
           <vendor>MonishVendor</vendor>
       </information>
       <resources>
           <!-- Application Resources -->
           <j2se version="1.6+" href="http://java.sun.com/products/autodl/j2se"/>
           <jar href="TestApp.jar" main="true" />
   
       </resources>
       <application-desc
            name="DemoName"
            main-class="GUI_QPDownloader"
            width="300"
            height="300">
        </application-desc>
        <update check="background"/>
   </jnlp> 

3. That's all. Now run jnlp file from any web-browser to test

How to create jar file for the java app you make.

Modifying a Manifest File

You use the m command-line option to add custom information to the manifest during creation of a JAR file. This section describes the m option. The Jar tool automatically puts a default manifest with the pathname META-INF/MANIFEST.MF into any JAR file you create. You can enable special JAR file functionality, such as package sealing, by modifying the default manifest. Typically, modifying the default manifest involves adding special-purpose headers to the manifest that allow the JAR file to perform a particular desired function.
To modify the manifest, you must first prepare a text file containing the information you wish to add to the manifest. You then use the Jar tool's m option to add the information in your file to the manifest.

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Warning:  The text file from which you are creating the manifest must end with a new line or carriage return. The last line will not be parsed properly if it does not end with a new line or carriage return.

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The basic command has this format:

jar cfm jar-file manifest-addition input-file(s)