Some time ago I wrote this manual in German, here is the English version.
You should have a photo on the Internet, either on a homepage or on Facebook or as here with me on Google+ Photos, then go on the selected photo and select with the right mouse button "Copy graphic address".
Then you go with Steemit on your profile name:
and then on settings
Then paste the address into the top box in Public Profile Settings
and then at the bottom to update.
