I am new to VBA, just got book yesterday.
Found some code for entering on a column works get all by itself, but does
not help with problem.
Also found code for a single cell accumulator, also work real well all by
itself.
Need to marry these two codes, so that I input on column C and get an
accumulative total on column F. Here are the codes:

Sub ChkColC()
If ActiveCell.Column = 3 Then
If Not IsEmpty(ActiveCell) And ActiveCell < "" Then
MsgBox "Has Data"
Else
MsgBox "No Data"
End If
End If
End Sub

-AND-

Dim Val
Private Sub Worksheet_Change(ByVal Target As Excel.Range)
If Target.Cells.Count < 1 Then Exit Sub
If Target.Address = "$F$4" And IsNumeric(Target) Then
Application.EnableEvents = False
Target = Target + Val
Application.EnableEvents = True
End If
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Excel.Range)
If Target.Cells.Count < 1 Then Exit Sub
If Target.Address = "$F$4" And IsNumeric(Target) Then
Application.EnableEvents = False
Val = Target
Application.EnableEvents = True
End If
End Sub

Need help please; thank you,
Jay