What you're trying to make is a panorama, but you're uploading your photos as a photosynth.
Photosynth.net hosts both
You can upload panoramas to Photosynth.net created in:
Microsoft ICE ( http://bit.ly/microsoftice )
Adobe Photoshop for Windows via this plugin: http://bit.ly/pstops
the mobile panorama apps http://bit.ly/photosynthforwinphone http://bit.ly/photosynthforios
and soon Windows 8.1 www.youtube.com/watch?v=Y5j7Fbx-Fh0&hd=1
For a perfect panorama, your camera's lens should not change height, latitude, or longitude (or change the focal distance or zoom in or out between shots).
For a better explanation about why keeping your camera's lens in one point in space is important for a good panorama, remember that panorama stitching is 2D stitching + foreground must line up with background the same in all shots, then read this: http://johnhpanos.com/epcalib.htm and watch these videos: http://bit.ly/howtopano