Here is an example of entering a date range for a Full Fiscal year, (for example, 2016):

Enter 01/2016 to 12/2017.

In this case, '01' refers to July, as it is the first month of the Fiscal Year.  
Any single digit month should be entered with the zero preceeding it (i.e. '02' is ok, while '2' is not).

Another option is to enter 'C/C' which is Current Month/Current Year.
'C-1/C' would be the Last month of the Current year, and 'C/C-2' would be Current month, two years ago.