You can supply descriptions for each of your products both in a long format and short format.  The long format description is displayed under the product description.

The short description is displayed with product options.

When entering entering both the short and long descriptions you have all of the normal editing tools that are found when editing a page including the insertion of images.

The entry for the long description is found at the top of the product page and the short description is found at the end of the product page.