How to find non ssl content on page

Enable Developer Toolbar in Chrome/Firebug bar in Firefox.
Click on Console.
It will show error details like this:

Mixed Content: The page at 'https://pinger.droidzone.in/' was loaded over HTTPS, but requested an insecure image 'https://i.creativecommons.org/l/by-nc-nd/3.0/80x15.png'. This content should also be served over HTTPS. https://pinger.droidzone.in/:132