Announcing documents
To allow other users to see the documents you want to share, you have to announce them by clicking on the Announce Toolbar button or pressing ⇧⌘E. After that others see your document in their Bonjour Browser and can connect by double clicking on it.

Inviting People
To invite people to your documents, just drag them from the Bonjour or Internet Browser to your document.

Joining documents
If you want to join a document on the local subnet, just doubleclick on it in the Bonjour Browser (⌘K). If you want to connect to a document over the internet, open the Internet Browser (⇧⌘K) and enter the sharing users hostname or IP address in the textfield.

Visible vs. Invisible.
If you want others to be able to invite you, choose "Always Visible" in the context menu below your name in the Bonjour Browser. If you need some privacy, choose "Visible if announcing documents".