JQuery :: Pass Parameters Into The Plugin?

I have been checking out the following sitepoint tutorial on creating a plugin using Jquery http:[url]....I have some Questions about the selector and the parameters.Say for example, I wanted to pass parameters into the plugin:

Code:
(function($) {
// jQuery plugin definition[code].....

And conversely if the plugin takes no parameters $(selector).MyPlugin(); Firstly is my understanding correct and secondly what if the plugin doesn't require a selector? What if it doesn't need to do anything to a given DOM element? would it be something like:

$().MyPlugin(someparameters)