FTC_WTFire7 You need to add a plugin to do that. This plugin came up with a quick plugin search, there are others out there. http://dev.bukkit.org/bukkit-plugins/messageoftheday/ %n% adds a line break if you use this plugin. (see documentation/config for more details)
He does not need an unnecessary plugin, it works straight from server.properties with color code and new line support, just less powerful. Just add "\n" when you want to break to a new line.