I went to my page at http://www.flickr.com , found a picture, clicked > All Sizes (above the picture), chose > Small (240 x 240).
Below the picture is "1. Copy and paste this HTML into your webpage:"
The code was pasted below and should show up as the image which should be linked to the Flickr page for that picture.
Note: The medium (500 x 500) image was too wide for this blog; only the left side was displayed.