Once you post the property details on Zillow you can easily go into the "Edit" function under the property detail for each listing and upload photos. Under Edit, click on "add/edit photos". Next choose the file(s) to add and click "Upload". The pictures may take a few seconds to load. Once the pictures are posted, you are free to rearrange them by dragging and dropping the images in the desired order. You may add a descriptive caption to selected pictures as well. Remember to save your changes at the bottom of the screen. Good luck!