SSB (Secure Scuttlebutt) is a peer-to-peer database, basically a database for distributed social-networked applications. Patchwork is the flagship application, a social sharing software. Like cjdns, to get connected to the SSB network you have to initially connect to a peer over the internet (a "pub server"), or over a LAN connection. However, unlike cjdns, once you are connected to the network, your node will discover other pub servers and connect directly to them.
Join the network
So, unless you happen to be on the same room as someone else running SSB/Patchwork, to get connected to the network you will need an invite to a pub server. Here is an invite code to my pub server accessible over cjdns:
To use the invite code, install and run Patchwork, and then click the "Join Pub" button and enter the invite code above. If the code doesn't work, contact me or ask in IRC for an invite code from someone else.