Choose wether to upload a portrait or not. When you choose to upload one, you can either upload a file from your computer (through the regular WordPress Media Library) or pick your WordPress user avatar, which can be defined in the WordPress Users settings.
If you’re familiar with Gravatar, your WordPress avatar may already have been defined, based on your email address.
Avatars have a defined size of 75x75px.
There is also a Read More link, that could point to an About page you may have previously created, or any other profile. Simply customize the URL field.