Where should I write this code?

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.validationsummary(v=vs.90).aspx
As per above link,the below code:
'Declaration <AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level := AspNetHostingPermissionLevel.Minimal)> _ <AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level := AspNetHostingPermissionLevel.Minimal)> _ Public Class ValidationSummary _ Inherits WebControl 'Usage Dim instance As ValidationSummary Should be added on the source view of login control page? ...