Here you can learn about, how to Map an organization group for an organization.
1. Login with Fresa Gold, Navigate to Master click Organization (Fig.1).
2. Select the particular customer (Fig.2)
3. Click Edit option (Fig.3).
4. Select the Group from the Group list and click Save changes button (Fig.4)
5. Now the customer is grouped under the Group (Fig.5)
Hope you got an idea about to create the customer under Group.