Sometimes the uploading process is stuck at 0% and nothing happens. Usually this problem is caused for your security settings of your browser, antivirus or firewall. The following instructions may help.
First, set your browser settings (Privacy) to accept cookies from Panoramio and try to sign-in. If that doesn't help, check your antivirus settings and add Panoramio.com to your list of trusted sites and try to sign-in again.