How do I add new links to the existing ones. Also how do I fill in the side panels with photos

You can use any of your Customizable Links pages to add new pages to your site:

1) Click Edit Site Pages
2) Activate any of your Customizable Links pages
3) Rename the link as desired

You can't really fill the right of the screen with photos, many people have resolutions where they wouldn't see anything to the right at all. However, you can use the Background Image feature (under your Change Colors link) to add graphical backgrounds to your site that will fill the rest of the screen at all resolutions.