Ok, had to go searching high and low to figure out how to get avatars here. Basically, it’s not stored locally. Instead, you need to set up an avatar here:
Gravatar – Globally Recognized Avatars.
To date, since it looks like I’m bending the rules of this thing, I can’t set up different avatars for the posters. Minor detail. If and when I figure that out, I’ll definitely fix that.