In the lower part of the left panel the assemblies of the currently selected system are shown. Assemblies can contain components and constraints. Everything that is put inside of an assembly can be moved together by selecting the assembly and modifying the origin.
The assembly origin should be moved to where the actual components in the assembly are located. This makes it easier to work with later on.
Click on the three dots next to an assembly to bring up options for adding components/constraints, renaming the assembly, and deleting the assembly.
The Duplicate option provides a quick way to clone components. Duplicate creates a new version of the component, with the text "_copy" appended to the component name.
Reparenting means moving a component between different parent assemblies.