on ebay you have the following choices:
1) you can upload 1 (just 1) picture from your computer to ebay for free. it will be automatically shown in your offer.
2) upload as many picturres as you like to some kind of webspace. maybe your isp grants you webspace or just get an account at tripod etc...
upload the pictures to that webspace with a ftp-program
in ebay, when inserting the piece description insert the following:
<img src="http://www.tripod.com/astupidaccount/myimage.jpg">optional clickable text</img>
change the url to whatever the location of your images is!