Bling! It is essentially an image editor but aimed at improving product images. It can be useful when you want to touch up photos and make them more attractive before posting them on a site like eBay.
The program essentially works in a four step process: delete background, compose picture, add effects, and see final image. All the tools are available from the left of the interface, and all you need to do is select one to apply.
A little pop up window on the right explains what every tool is. I suggest closing it though as it crowds the interface a bit. There aren't that many effects to work with but they're all easy to apply.
Don't get confused though, Bling! It won't improve the appearance of your product. It's only limited to spicing up the background. The program does a good job at outlining the existing background and removing it, however make sure you have a good new picture to work with as effects in the program are fairly limited.
Although it's fairly easy to use and outlines backgrounds well, Bling! It is a fairly limited image editor. If you're really looking to improve your product images, use a more powerful application.