Ergo is all local to the server. It doesn't do any server-to-server communication.
Users first connect, then set their nick with
/nick <new nickname>
Then register that nick with:
/ns register <password>
or if that doesn't work your on your client:
/msg NickServ <password>
Then quit with /quit
Now reconnect with SASL. In irssi, start again without connecting and run:
/network add -sasl_username <nickname> -sasl_password <password> -sasl_mechanism PLAIN <network>
/server add -auto -net <network> -tls -tls_verify <server hostname> 6697
/save
where <network> is by default ErgoTest, but may be configured different.
The user then has full authority to do stuff on the server.
You can set your account as always-on so that you stay in channel lists and receive private messages, even when disconnected:
/ns set always-on true
You can create a new channel with
/join <#channelname>
and register it as permanent with
/cs register <#channelname>