To create a Reporting Group first go to the Reporting Groups page under Site Admin. With your organization's name highlighted, click on the Create a Group button.
On this page enter in a group name and description (optional). Then click Create Group.
To edit a Reporting Group select the Reporting Group in the tree view, then under Description select Edit. This will give you an option to change the group name or description.
You will also have the ability to move the Reporting Group underneath an already created group. This gives you the ability to easily change the structure of your Reporting Groups at any point.