How do I set AppSettings in an ASPX project's Configuration manager

[Lapple46]

This is an ASPX/CS Project with Visual Studio 2010. It is a Configuration Manager question.I am successfully debugging (sort of) some code that is being used already on a server. But there is a piece of code that plays with the URL in the live version that should not be used in the debug/localhost version.\[code\] protected void Page_Load(object sender, EventArgs e) { if (ConfigurationManager.AppSettings["IsTesting"] == "false" && Request.Url.ToString().Contains("http:")) { Response.Redirect(Request.Url.ToString().Replace("http:", "https:")); } LoadMasterTemplate(); }\[/code\]This piece of code lands on the "Response.Redirect...." line when it should not because the "IsTesting" app setting should be set to true in the ConfigurationManager . How do I set that?