If you want to put your own pics on ebay and not use their system first your pics must be hosted somehwere on the internet. A good, free place to host some pics would be to create a photobucket account (www.photobucket.com)
Then once you have the pics hosted, you have to type in the addresses for the pics in the description of the item by using HTML (Don't worry ebay has little things you can click on which will tell you how to put in the HTML for adding a picture) Just follow their directions and make sure the pics show up on the preview screen before you confirm the listing. If the pics show up as little red X's or all you see is weird HTML writing, then you have made an error, then you have go back and make sure everything is correct.