To add a picture caption, you will need to click on "Products >
View/Edit Product" from your admin area and then click on a product to
edit from your list of products. From the next page, you will need to
scroll down to the bottom section that says "MANAGE IMAGES for this
Product". In this section, you will notice a column that says "Edit
Info." Click on the icon below that column and to the right of the
appropriate image that you would like to add/edit the picture caption
for. You can make your changes to the picture caption from the next
page and then click on "Save Changes" when you are done.
You can now view your website and take a look at the product that you just edited the picture caption for.