To add an account to an OU, perform the following steps:

1. When an account is initially added to your organization, it will be a child of the organization root. To add it to the OU you just created, you need to move it using the following CLI command:

        aws organizations move-account 
          --account-id <twelve-digit-account-id> 
          --source-parent-id <root-id> 
          --destination-parent-id <new-parent-ou-id>

2. If you wish to move an account from one OU to another, simply use the same command but with the existing parent OU ID instead of the root ID.