You can create a mapping in the Mapping Editor by drag and drop or using the Create Mapping tool or contextual command. To generate default mappings between source and target objects that have the same name, right-click a data source and select Generate Default Mappings.
When objects in the Source and Target pane are mapped, any sub-objects that share the same name are automatically mapped as well. You can force the mapping with the Generate Mapping tool in the Sub-Object sub-tab of the Mappings pane.