Code:
on *:join:#: {
  if ($nick != $me) && ($chan == #chat18+) {
    if (!$isfile($+(join.txt))) { write join.txt }
    if ($nick isin $read(join.txt, w, $+(*,$nick,*))) { describe $Chan Hey $nick $+ , Welcome Back. :)    }
    else {
      describe $chan Hello $nick $+ , Welcome to $chan $+ . May we have your age Please ?
      ;write join.txt $nick
    }
  }
}
menu nicklist {
  Add user:{ write join.txt $1 }
}

Just copy and paste, don't change anything and see if it working as you want it to smile

right click in the nick list and you should see the menu there, the nick you have highlighted will be the one you add to the list..

if ($me != tired) { return } | else { echo -a Get a pot of coffee now $+($me,.) }