You mean like the profile-image at the right at service.mendixcloud.com:
Not available by defailt in Mendix. You have to do quite a lot of building and style-adaptations to your page layout, probably the page layout you use is Atlas_TopBar. Which is why I built a navigationbar-addon myself and made it available in the marketplace free to use.
Simplest way is to download module SystemManagement and use page layout ‘Atlas_TopBar_WithUserAccountInformation’.
Or download the Base application and see how it is implemented, or use it as starter-app.