Replace three thumbnails at bottom of page?

Hello! I've read through the instructions but must be missing something (repeatedly :S) I'm attempting to replace the three smaller images at the bottom of the page (Catch Everest) - the Nepal Prayer Wheel, Mount Everest and Mount Kanchengjunga -but cannot locate where they are. I've figured out the image slider - but I just need help with updating those images. It's driving me batty! Thank you!