Magento Store - Change Navigation Menu to Include Sub Menus

We have setup a Magento store and have everything up and running except for some menu customization. Currently the menu only shows top level navigation at the top and then you have to click further to get to second and thrd level navigation. We want the second and third level navigation to show up automatically when someone clicks on a link for a section of the website. We understand the types of changes that need to be made but we need someone with programming experience in Magento to make those changes. Note: You must have examples of prior Magento experience to be considered. A bonus would be to show examples where you've created such a navigation system.