I think you are looking for the ActiveSheet Property. If you
search on "ActiveSheet" in VBA Help, and choose "ActiveSheet
Property", you will find what you need including this Example:

****************************************************************
This example displays the name  of the active  sheet.

MsgBox "The name of the active sheet  is " & ActiveSheet.Name
****************************************************************

So, for your application you want to find the Sheet.Name that
matches ActiveSheet.Name and then take the appropriate action.