To change the pictures in the slideshow on your home page, you will need to delete the current images, and then add new images your store’s theme.
To do this, go to the “Design & Assets >> Theme editor” section of your toolbox, in the “Theme Assets” section on this page, you will see the five slideshow images…
Click on each of these images, and delete them individually in the popup window that displays.
Your new images should be sized at exactly 960px × 303px. You will need 5 images (unless you want to change the number of images in the slideshow which is more complex to do).
Name each of your images with the same names that the original images had…
… and then upload your images in the “Upload a new theme asset” section of this page.
You new slideshow images should now be displaying on your home page. If they are not, hold down the SHIFT key in your keyboard and click your browser’s refresh (or reload) button to reload your computer’s cached version of the page.