MyAdBlock doesn't allow you to mark a picture as a favorite, at least not yet.
What about downloading your favorite pictures? Keep in mind that the pictures we use are sized to replace on-screen ads. That means they are too small and odd-sized to serve as wallpaper for your computer or phone. We suggest you do a Google image search to find additional sizes instead of downloading MyAdBlock pictures.
Move your cursor over the picture to show MyAdBlock's picture controls. Click the eye icon to open the picture in a new tab. Then right-click the image and select Search Google for image.