You cannot. Applet security is simply so strict that, unless the applet is signed, you cannot access any resources other than those from the same server that the applet is running on. That means no access to the client's file system, no access to databases, no access to FTP servers, no access to other web servers, etc.
Tutorial? I just looked in the Ant documentation and found there was a "signjar" task. Of course, probably you haven't yet set up the things you need to sign the jar with, in which case you would have to do that first. If that's the case then your google keywords to find a tutorial are "jar signing tutorial".
The HTML element you use to specify the applet to the browser has nothing to do with any of that.
Edit: It just occurred to me that you question might also be "How do I run an Ant task in Eclipse?". You should really take more time to write a clear question rather than making us guess.