
You create a requirement set at the root level or within any other requirement set.
To create a root requirement set...
Alternatively, you can right-click on any requirement and select the entry New → Requirement on Root Level... in the context menu

To create a new requirement set within an existing requirement set...
Alternatively, you can right-click on he requirement set in which you want to create a new requirement set and select the entry New → Requirement Set... in the context menu
Now, the forms editor opens for the creation of new requirement sets. Enter the name of the requirement set and, optionally, a description and save the requirement set.