I'm assuming you clicked the SHARE tab in order to put your family info on their site. Did you then click on the line that says "if new user, click here" ? Do you have cookies enabled on your browers? I noticed it asked me if I would allow a cookie, before it went to the form to fill in user information.
If you have cookies enabled, and you clicked on the line I mentioned above, and you still have a problem, try sending email to Webmaster@familysearch.org Be sure you list step by step in detail what you did, so they can id the problem.