When you display your pics on your computer, are they small? If so, you need to fiddle with the resolution on your camera settings. Resizing a small picture to be larger almost always results in a poor image.
If your pictures display at a decent size when you view them on your computer, then there's something wrong with the website's uploading process.
If your pictures display at a decent size when you view them on your computer, then there's something wrong with the website's uploading process.