no need for a tutorial
/join #yourchannelname
Type the above in mircs main editbox in the status window
if you would like to create multiple channels(no flooding help intended)
/join #channel1,#channel2,#channel3
most servers also have channel services which allow you to register a channel which will keep it open when theres no1 in the channel and various other features, but youll have to ask about this on the server you go on.
if your still confused type: /help /join in mircs main edit box.