The program will know the time span if else vb.net - vb.net

Question

I dont know how it is called thats why I called it time span.
I don't have any idea yet how to code it but this is what i want to do
Dim sy as String
If (June 2015) to (March 2016) Then
sy = "2015-2016"
End if
I know it is simple but i dont know how to code the June 2015 to 2016
Thanks in advance for the help
Edit :
Now i got to this code
I uses to do this
Dim value as DateTime = New DateTime(2017, 4, 1)
Dim value1 as DateTime = New DateTime(2018, 4, 1)
Dim sy as String
If my.computer.clock.localtime <= value then
sy = "2016-2017"
ElseIf my.computer.clock.localtime <= value1 then
sy = "2017-2018"
Else
msgbox("Check your current date")
End if
But when the computer's time changed to 2015 it shows "2016-2015"

Answer 1

So I use 4 textboxes to supply the data you need as variables. 2 for the years and 2 for the months. Also you need to think of how many moths left in the yeae and add the month number of the next year. If you span more than one year you have to account for this as well. O.K here is the snippet without error checking in a button event:
Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
Dim firstÝear As Integer = CInt(TextBox3.Text)
Dim secondYear As Integer = CInt(TextBox4.Text)
Dim firstmonthnumber As Integer = CInt(TextBox5.Text) 'months number in first year
Dim secondmonthnumber As Integer = CInt(TextBox6.Text)
Dim d1 As DateTime = New DateTime(firstÝear, firstmonthnumber, 1)
Debug.Print(d1.ToString)
Dim d2 As DateTime = New DateTime(secondYear, secondmonthnumber, 1)
Debug.Print(d2.ToString)
Dim M As Integer = Math.Abs((d1.Year - d2.Year)) - 1
Debug.Print(M.ToString)
Dim myYear As Integer = 12 - firstmonthnumber 'month left to the end of first year
Dim months As Integer = ((M * 12) + Math.Abs((d1.Month - d2.Month))) + myYear
Debug.Print(months.ToString)
End Sub