play with URL in class librarry

hi everry one
i hope you well ......
i have class librarry named UI and i have class "ConnectionSettings.cs" with the following code:
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
/// <summary>
/// Summary description for Connection
/// </summary>
public class ConnectionSettings
{
    public static string GetConnectionString()
    {
   
        String ConnectionString = ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;
        return ConnectionString;
    }
}
Iwant to chec ...