Automatically login website using asp.net

when i click the Url in the list i want to open the url in new tab also login automatically.
If it's a Forms Authentication, pass the username & password as querystring in the URL.

Then, all you need to do in your page load is something like:

string username = Request.QueryString["username"].ToString();
   string password = Request.QueryString["password"].ToString();
   if (Membership.ValidateUser(username , password))
   {
         FormsAuthentication.SetAuthCookie(username , true);
         Response.Redirect("~/");
   }

Other way could be to use HttpWebReqest and HttpWebResponse, pass appropriate parameters of the page while crawling using code behind.
See these samples:
VBASPNETAutoLogin Overview[^]
HttpWebRequest Post method[^]