The Team tab provides you with contact details and role information for the other people with permissions to work on this project.  Usually the list includes just users with interactive capabilities (those with Manager and Team licences) but if you untick the check box at the top of the list all View only type users will be shown as well.

Simply click on a user to see their contact details to the right, from there you can contact them by email or using any of their social media contacts.  To update your own contact details on the Browser app use the User tab.