Read the docs? Their API is C based so it's not necessarily as easy as a Node.js or Ruby programmer might be used to. They do have a P2P chat program built on-

Read the docs? Their API is C based so it's not necessarily as easy as a Node.js or Ruby programmer might be used to. They do have a P2P chat program built on-top of it so you can use that as an example and I think someone did their thesis on building a "facebook for GNUnet" on an older version. Not sure if that code is public though (it most likely is, I just don't know where).