Another group of explorers has arrived. Welcome!

@Cat Gun         
@Walkaway guy          
@You're kidding, surely.          
@Dan Woloz          
@Calculator Music Appreciation Society          
@Kitt McGregor          
@Orestse Kyriakos Poulakis          
@La LibreRie solidaire
Hi Administrator, me again, sorry for all theses questions, I'm beginner in Hubzilla
To post on the channel, I have to add this channel as friends/contacts, and wait for the support admin add me ? Is that the way ? And after, I can mention this channel with a ! ?
@"La LibreRie solidaire"  Yes.  Go to that channel (, and click Login (upper left).  There will be a button labeled "Remote Authenticate".   Click that button, and it should authenticate you to that hub.  Then go back to the channel, and you should see the "Connect" button under the channel avatar photo.  Click connect.  Then you should be able to post to the "Hubzilla Support Forum" by typing the name of the forum in quotation marks, preceded by the bang symbol (!)
He's right. However, if you follow the link in my response above, you should be automatically authenticated without the extra step. This is because links can be appended with your "zid" that lets the remote hub know how to request your identity.