Create the organizational units in AWS Organization

On the AWS Organizations console, choose the Organize Accounts tab and then choose + New organizational unit.
For the name of the OU, enter Production and then choose Create organizational unit.
Choose your new Production OU to navigate into it and then choose + New organizational unit.
For the name of the second OU, enter MainApp and then choose Create organizational unit.
Now you can move your member accounts into these OUs.
In the tree view on the left, choose the Root.
Select the first member account, 222222222222, and then choose Move.
In the Move accounts dialog box, choose Production and then choose Move.
Select the second member account, 333333333333, and then choose Move.
In the Move accounts dialog box, choose Production to expose MainApp. Choose MainApp and then choose Move.