Creating and Changing Patterns

Here are links to videos further explaining how to create patterns....


Basic ideas- https://helpx.adobe.com/illustrator/how-to/define-pattern.html

A bit more advanced techniques here @http://tv.adobe.com/watch/learn-illustrator-cs6/creating-a-repeatable-pattern-for-the-web/

And here is a close up of the "Pattern options" pallete-