Read Variable from Web.Config

Given the following web.config:

<appSettings>
     <add key="ClientId" value="127605460617602"/>
     <add key="RedirectUrl" value="http://localhost:49548/Redirect.aspx"/>
</appSettings>

Example usage:

using System.Configuration;

string clientId = ConfigurationManager.AppSettings["ClientId"];
string redirectUrl = ConfigurationManager.AppSettings["RedirectUrl"];