// Add this on the beginning of your .cs code file
using System;
 
 
// Use this line when you want to save a cookie
Response.Cookies["CookieName"].Value ="CookieValue";
// How long will cookie exist on client hard disk
Response.Cookies["CookieName"].Expires = DateTime.Now.AddDays(2);

// To add multiple key/value pairs in single cookie
Response.Cookies["EmployeeData"]["FirstName"] = "Mark";
Response.Cookies["EmployeeData"]["LastVisit"] = DateTime.Now.ToString();