1/ Click on one of your listings and go to 'Edit'.
2/ On the right hand side of the edit page you will see a box 'eBid store category. Choose eBid store to stock'. Pick your store then use the drop down box to pick the category you want to put your dress in.
3/ Go to the bottom of the page and click 'Save'.
This will put your item into your store. For future listings remember to do this when you are creating your listing.