1: write Cookies

Response.Cookies["UserName"].Value="Guest";
Response.Cookies["UserName"].Expires=DateTime.Now.AddDays(1);

Step 2: add Cookies

 HttpCookie userName_zhengshu_Cookie = new HttpCookie("uname");
        userName_zhengshu_Cookie.Value = " Chen xx";
        HttpCookie userLession_zhengshur_Cookie = new HttpCookie("lcode");
        userLession_zhengshur_Cookie.Value = "chen jian ping";
        userName_zhengshu_Cookie.Path = "/";
        userLession_zhengshur_Cookie.Path = "/";
// Limited period of validity
        userLession_zhengshur_Cookie.Expires = DateTime.Now.AddDays(1);
        userName_zhengshu_Cookie.Expires = DateTime.Now.AddDays(1);
        Response.Cookies.Add(userLession_zhengshur_Cookie);
        Response.Cookies.Add(userName_zhengshu_Cookie);
//Cookies add
 Response.AppendCookie(user_cookies);
// The values
Response.Write(Request.Cookies["uname"].Value);

//javascript Write to read Cookie
function Set_Cookie()
{
    var setValue=" Chen xx";
    var exdate=new Date();
    exdate.setDate(exdate.getDate()+365);
    document.cookie="userLession"+ "=" +setValue+";expires="+exdate.toGMTString()+";path=/";
    alert(" Has been written to Cookie");
}
 function Get(){　     
   　　var cookieString=new String(document.cookie)     
   　　var cookieHeader = "userLession="     
   　　var beginPosition = cookieString.indexOf(cookieHeader)     
   　　if(beginPosition != -1)
   　　{     
   　　　　alert(cookieString.substring(cookieHeader.length,cookieString.indexOf(";")));  
   　　}     
   }