New business units can be created in the Admin area. Click Admin > Settings. The very first panel at the top will allow you to create a Business Unit. Once you create a Business Unit, Create the Divisions to go with it and then assign users to the Divisions. The process for a new Business unit is: 

1. Create Business Unit 
2. Create Divisions 
3. Assign Users to Divisions 
4. Create Workflows
5. Check all settings