I assume you're using version 0.90 and above.

GTKG will acquire IPs automatically. You simply need to be sure that you can make outgoing connections to the Internet.

Start gtk-gnutella, and leave it running for a while. As soon as it makes a connection, it will acquire more IPs.

Don't follow the suggestion of the Unregistered user: all Gnutella programs need to bootstrap, and all have the same algorithm to do so.

-- Peer