If you post mulitple ads, only the latest will be shown on the front page. In order to delete or edit your ads, login if necessary, go back to the classifieds, click on My Ads. You should see a delete/edit associated with each ad.  If you need to resize your photos and don't have an photo editing package, you can download a free for personal use image resizer from http://www.vso-software.fr/products/image_resizer/