Adding running total macro

Hello All,

I want to modify this code to add a running total of column A on column B rows every time I add a value on column A. Cell B2 has already been set to a specific value. So I would like the code to start adding B2+A3 instead of A2+B2. I'm tucking this to a button.
Screen Shot 2016-04-15 at 1.09.45 PM.png

Sub Test()
Dim Coin As Long
Dim Total As Long
Dim Demand As Long


Demand = Cells(2, 3)


Total = 0


For Coin = 2 To Cells(Rows.Count, 1).End(xlUp).Row
    
    Total = Total + Cells(Coin, 1)
    If Total > Demand Then
        Cells(Coin, 1).Interior.ColorIndex = 6
        Total = 0
    Else
        Cells(Coin, 1).Interior.ColorIndex = xlNone
    End If
Next Coin
End Sub

Thank you!