This tool will help you move your community off of Ning and onto your new Spruz Powered site. When a logged in user on your Ning site clicks the link they will be directed to your registration page on your new site. Most of the information will be auto filled in with the users existing info on your site, even bringing over the person's profile pic.
On the left enter your new site URL. Then Choose a display type. Copy the code on the right and paste it into a custom box on your site. Be sure to test the link once after adding it to make sure it is going to the correct place.