It is easy to invite your manager to join Atlas Objectives. Just go to your My Account tab and look for the "Invite Your Manager" button.
Click on that to send an email to your manager to join Atlas Objectives. When your manager joins they will automatically have you as one of their team members and can see your objectives.
After your manager joins Atlas Objectives they will have the Teams tab that allows them to invite their other team members into their Atlas Objectives account.