If you want to add user to your account, you have to create user's role first, where you can specify rights you want to assign to the user with this role. To do this, select "Create Role" on the left side panel in the Administration section. Enter the name of role, mark checkboxes for the appropriate rights and click "Save" (If you want to know more about how this rights work, visit "Create Role" section of User Guide).
Then go to the "Create User" section. Fill in mandatory fields, such as Username, First name, Last name, Email, than enter the password and confirm it. Mark "Access owner" checkbox below if you want this user to have access to your campaigns on AdsBridge. Then choose previously created role from the drop-down list. After you've done, click "Save" button. Congratulations, a new user has been successfully created!