Damn. Stop it. Jtella is 3 years old. It doesn't support the latest gnutella standards so it can't connect! Gnet apps now use gwebcaches to connect. But even if you get Jtella to get hosts from them, no Gnet client would support connections to your client. If you want a open source java app to work on, there are two:
1) Phex
http://phex.kouk.de/index.php
2)Limewire
http://www.limewire.org/
LW being the most up to date and worked on open source java client. Your help would most benifit to Phex though.
Ciao