You can create new objects in the configuration diagram using the Create menu. The Create menu has individual menu items for each type of object.
All other objects are created by editing the object that contains them. The main dialog for the containing object allows you to navigate to other dialogs in order to create the contained objects. For example, you can open the Partitions and CHPIDs dialogs from the Processor dialog in order to add Partitions and CHPIDs to the selected processor.
You create an object by filling in details in the appropriate Create... dialog and pressing OK. See the details for the specific Create... dialog in Modifying objects in your configuration.