The info that is used to show your name and picture in the branding bar is drawn from the account owner information in your contact manager.
From the "Branding and Variable" section of the dashboard, you can click the link to "My Name, Company Name, and Photo" which will show you your contact info in your contact manager.
This is where you can upload a new photo and change the name that's being displayed, it should already have this info from when you signed up, but if you want to change what's being displayed this is the place to do it.

