Your question is rather vague, but the core of the answer is to use
the Change event to execute the appropriate code when a value on the
Summary sheet is changed. Right-click on the sheet tab of your Summary
sheet and choose View Code. In the code module that opens up, enter
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Cells.Count > 1 Then
Exit Sub
End If
If Not Application.Intersect(Range("A1:A10"), Target) Is Nothing Then
' your code here
End If
End Sub
This code will be automatically exectued when a value on the worksheet
is changed. The code test whether the cell that was changed (Target)
is within the range A1:A10 and if so then executes whatever you put in
the line ' your code here.
The Change event is triggered when a cell's value changes as the
result of the user typing in a cell or as the result of other VBA code
modifying the value, but not if the change is simply the result of a
calculation.
Cordially,
Chip Pearson
Microsoft Most Valuable Professional,
Excel, 1998 - 2010
Pearson Software Consulting, LLC
www.cpearson.com