Create a new department

Organization-->select the organization unit to be extended-->Add Dept-->Enter details like Name and Description

OUM-server

Notice: In this case, MyTest Co. is regarded as the top level of an organization. So departments should be added under this level similar as the default organization layout. Of course,you can change the name as you want by using dept settings.

Following is an example of adding department IT to this company:

OUM-server

From client end you have this view:

OUM-server