Sessions are amounts within charges that are specific to timing.  In the creation of a session you need to select the dates and times for recurrence based upon the amount within the charges previously created. Attendees can also be adjusted here. 

Session names can be as specific as necessary and based in your current timezone.  They can be reflective of timing to indicate a specific date range.  They will be seen only on the Revenue Report and will not be seen in a family's billing detail.