Help adding an Image

I'm trying to put an image in a thread, but I don't know what the source is when I click Insert/Edit Image.  Am I doing this wrong?

Thanks for the help.

In most browsers you can right-click on the picture you want to include and click on "View Image". Then paste the URL bar into the Insert/Edit box.

Edit: in pictures for example, if I wanted to add an image of your avatar (in Firefox, I know Chrome also works similarly though):

Right Click and View Image

Copy URL

Insert Image

Gets this as the result:

You rock!  Thanks!