If your item matches more than one category, and you have duplicate items, list it in more than one category. Please list no more than three duplicates in any given category. This is completely optional, if you are not comfortable working with pictures, you can leave this blank. If you have never done this before, it can be a little tricky. Ideally, the resolution of your picture should not be any higher than 72dpi because that's all a computer monitor can display from a web page.
Any higher resolution is just a waste of file size.
An ideal size is about 200 to 300 pixels wide. Putting a larger picture with your listing will slow down the page loading time so much that you will lose potential bidders who will not wait for it to load. Now you need a place to store your picture at a web host site. MysiteInc BidBay will host your images and provide you with free counters for your auction items. TerraShare Melonbones is also currently offering to do this FREE of charge for a limited time.