• Add server

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

• Automatically connect at startup

/set irc.server.libera.autoconnect on

• Join a channel automatically

/set irc.server.libera.autojoin "#linux,#weechat"

• Add your nickname

/set irc.server.libera.nicks YourNick
/set irc.server.libera.username YourNick
/set irc.server.libera.realname "Your Real Name"

• Save configuration

/save