Hi IzzyLeft,
You can find some good examples in the help file, type /help remote and you will see some good examples, the bit your looking for is under on join.
Heres a small sample you can use to get the general idea in the meantime.
;when someone joins your channel, send them a simple greeting
on 1:join:#yourchannel: msg $nick hello welcome to my channel!
Just change the #yourchannel to the name of your channel including the # prefix i.e. #Dizzystub
also change the message after $nick to whatever you want.
Hope that helps!
Best regards,
Diz