The ability to invite users and manage their access to your application is one of the core elements of e-satisfaction.com, as this is what helps feedback flow in the organization. This is normally done by clicking on this "Users" icon that is located in the "Configuration" panel of your application, which takes you to the Users list that is shown in the following snapshot.
From this screen you can add / invite new users by clicking the "Add user" button. However, it is possible that you do not see this button. If this happens, most probably you do not have the right to add a new user.
At e-satisfaction dashboard, each user is associated with specific Roles n Rights. Therefore if you are not the owner or/and the admin of application, you don't have the right to add a new user to the application and that's why you cannot find the add user button on your dashboard.
To validate that this is the problem, you can check your role from application's users list and see if you have the owner or admin role. If you do not have this role, please contact the admin or the owner of the application to assign you the role you need.