To Make a Thumbnail
Once your image is uploaded, you can make a thumbnail that will appear in the list view of the images. Many sites use the thumbnails to conserved space. To make a thumbnail, click on the image detail page—the same page you see once you have uploaded an image. Type in the demensions of the thumbnail, between 75-200 is usually a good size. You can also crop the image if demensions are an issue by selecting the Crop checkbox. Click Create.
The page will refresh and you will see the thumbnail created. You can resize it if you want, just follow the same steps. If you would prefer a different thumbnail that you created in another photo editing software, you can upload this instead. Browse to the file from the Upload Thumbnail box and click Upload. This is not recommended.