Customizing the Design of the Page Menu Bar

I was wondering if there is anyway to change the current page menu bar to look more like tabs. I want it to look like this:

http://eastsideelementary.com/newsite/menu_tabs.jpg

I have designed websites before using Dreamweaver, so I know the basics of CSS and HTML. This is my first time using WordPress, will it be hard to make the page menu to look like this?

Thanks so much!