using WeeChat for example.

add server and connect

/server add libera irc.libera.chat/6697 -ssl
/connect libera

register nickname

/nick stefan736
/msg NickServ REGISTER xxxxxxxx you@example.net
/msg NickServ IDENTIFY yournick xxxxxxxx

automatically use nickname and identify

/set irc.server.libera.nicks "yournick"
/set irc.server.libera.command "/msg NickServ IDENTIFY yournick xxxxxxxx"

join channel, have fun

/join #linux