Find a java applet on the web.
Copy the URL of the webpage containing the applet to the "URL of webpage with applet:" field above and submit. I will automagically extract the applet from the page's source.
Open the source of the page. If you're using Safari go to View > View Source. If you're using Firefox go to View > Page Source. If you're using InternetExplorer go to View > Source.
Find the <applet ... > tag.
<applet ... >
Copy the code parameter in this applet tag: whatever's in quotes after code=.
In the same applet tag, copy the codebase parameter if it exists: whatever's in quotes after codebase=. If there isn't a codebase parameter then use the URL of page up to the last "/" instead. That means if the URL is "http://google.com/java/applet.html" then you'd use "http://google.com/java/" as your codebase. Important note: If the codebase field does not start with "http://" then take the URL of the page the applet is on up to the last "/" and prepend that to the codebase. So, if the applet is on "http://google.com/java/applet.html" and the codebase= parameter given is "sub/folder/", you would use "http://google.com/java/sub/folder/"
Copy these into the "Code:" and "Codebase:" fields above and hit submit.
(Alternatively if you know the codebase is the same as the page the applet's on then just tack the code parameter to the end of the url and submit that in the "Path to .class file:" field above. In other words, you can just submit a URL to the applet's main class file in the "Path to .class file:" field.)
Note: Capitalization in the fields and URLs matter.
Check out my php source.
The <applet> must appear in the source of page that appears when you view it on your browser, which is not neccessarily the same as the source at the given URL.
Maybe the URL you gave is redirects. In that case you must give the final redirect URL
Or maybe, the applet appears in a <frame> within the page you think it's in. Try right-clicking near the original applet and selecting "Open Frame in New Window" or "This Frame > Open Frame in New Window". If you don't have that option then look through the source of the page, in which case you may find something like: <frame src="applet.html">. Switch or add this .html name to the end of your url and try that.