[Theme: Ready To Be!] How do I extend the main menu?

Hello,

I’m building a website with a store/e-commerce template and for some reason it can’t hold all categories/sub-categories under the categories drop down list without deleting a few from the bottom as I keep adding them. So I’m trying to extend the width/height of main menu tab or even the main page width so as to accommodate all categories under the blue background. Is there anyway someone can help me with that? So far all my attempts only extend the main menu to the right and out of the page…

I hope all that made sense…

Thanks in advance

My website is: http://www.4evertagsale.com