Custom buttons to replace the main menu bar

Hello, I'm looking to replace the entire menu bar (www.chocolateatime.com - the menu bar right below the header image) with my own buttons that I created in Photoshop. For example, I created a 'Running' button in Photoshop (saved as a JPEG) and I would like to place it right below the header image (along with other buttons). The user can then click on the button image and will be taken to the 'Running' page. I'm not good with CSS or HTML code so detailed help would be much appreciated!