On the sidebar menu, the second option you will find is Package groups. After you click there, a “Create package group” button will appear on the right side. Click there to start setting up a new Package Group.
Next step is to simply enter a name for this new Package Group. The best practice here is to set a name that references the exact Wash Package that will be related to it. For example, if you have a wash package called Basic Wash, and you plan to offer this wash in multiple sites, then the Package Group for it should be called Basic Wash as well.