That will probably work too, but for them to be visible to folks, they have to have a publicly accessible URL. For example, if you drag a photo from your computer to here (if it lets you in the first place), it will use something like "file:///home/username/mypicture.jpg" which will fail to be sourced correctly for pretty much anybody except for your computer.

So: you can drag stuff from other web pages, and verify they have a URL associated with them by right clicking on the image within the comment box and clicking "Image Properties." There is no handling, however, for uploading an image to the idkfa server, aside from user avatars.

Another reason I recommend Google or Flicker is because they tend to not care about people "hot linking" images from their sites, whereas others (including idkfa itself) return an error message when it detects that an image on their server is being used from somewhere outside of their site.