I’m pretty new to WordPress; the older versions of this site used a custom application I wrote using .NET which I just didn’t have time to maintain anymore. I started porting over all my posts and comments and noticed it always shows my profile as the default “unknown” icon.
First step to fix this is to sign up here at Gravatar. You create a profile using your email as your unique identifier and upload the picture to use. After you do that, you can verify access which allows the blog to display this picture of you. You go to Edit My Profile > Verify Services, then pick “WordPress” and click add. Put your blog URL and the credentials to login and that will do it.
Just one last note: you’ll need to have XML RPC support enabled for this to work (you may have gotten an error in step above if it’s not enabled). You can enable support in WordPress under Settings > Writing > Remote Publishing. Here’s a link to a great article by Go Daddy that explains what enabling XML RPC support does.