this is Rob demonstrating the image thumb to large version
Step 1 choose the image in it's large version, give it a meaningful name, put in directory on your desktop for upload
Step 2 go to the page where the image is needed- Insert / Edit image, browse the server to find the images(content) folder choose the image at the size you want , in this case I chose size 3, save
screen shot of choosing image size:
Step 3 click on the image and link it to the original image, you will get a list of images so the file name is critical.
Step 4 save the page