jar signer and private key usage

[rajesh godbole]

Hi all,
I have developed a site and using java web start to down load the thick client. This Client jar is signed using jarsigner which is created using keytool on my local machine.
Now I want to use some security in this. I am not understanding the exact usage of this private/public key. I am not sending any public key with jar. What more is required to do? In real life how is this managed ?
Thanks in advance
-rajesh