Code:
on *:start:{
  server irc.rizon.net
  server -m irc.ogamenet.net
}

on *:connect:{
 if ($network == rizon) {
   msg NickServ IDENTIFY pass
   join #GrosCuls,#eFrance,#famille-en-chocolat,#laroulotteroumaine,#minsol
 }
 if ($network == ogamenet) {
   AuthServ auth ouraios pass
   join #ogame.fr,#fr.uni64
 }
}


See:
/help $network

You can join multiple channels in a single line.

Its best to join the channels in as few commands as possible than one join per channel as that can cause 'flooding' once you hit a certain number depending on the networks flood settings (if they have any).