WordPress allows users to have an avatar/profile photo and having your own image instead of the ‘mystery man’ will set you and your showcase apart from the others.
In the user profile area there is a change avatar area to upload and change your avatar. However that one is not very user friendly (image cropping is difficult at best). Instead go to the extended profile tab and use the ‘Profile Photo’ area to update/change your avatar/profile photo.
Tip: It is recommended to use an image that can be cropped into a 1:1 aspect (square) image for your avatar/profile photo.