Search the HTML on the page for 'http:' to locate the non-secure items. Either remove these items or make them secure. 

  1. Right click on the page that displays the error and choose view source
  2. Press Ctrl + F on your keyboard
  3. Enter http: in the search filed
  4. Click Find Next and search for a hyper link URL that is nonsecure and points to a file such as flash files, image files or HTML files
  5. Replace the http: with https: on any insecure links