It took me a while to figure it out but what you have to do is
1 Go to WordPress.com
2 Create an account using the email address as used when registering with Fiddlehed.
3 Add the image that you want to use on Fiddlehed on your new WordPress account.
3 Once you have done all that (Saved, confirmed etc), log into the Fiddlehed site.
5 Go to your account and the image you want should be there.
Thanks for the tip, but anything that requires yet another registration, a personal account, and providing yet more personal information… I’ll pass. I would vastly prefer that the webmaster of this site provide a direct way to replace the user icon with a photo.