How to scrap a website which is having login security

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C#

Hi
I have some doubts in website scraping.
I can able to scrap a site which is not having login.
But i cant able to scrape a page which is having login.
The scraped site which is having login is only showing the login page.But i need some page which is found after login page.
Can you please make the needful to scarp a site which is having login security.


Thanks in Advance

What I have tried:

string formUrl = "site url"; // NOTE: This is the URL the form POSTs to, not the URL of the form (you can find this in the "action" attribute of the HTML's form tag
string formParams = string.Format("email_address={0}&password={1}", "mail id", "Password");
string cookieHeader;
WebRequest req = WebRequest.Create(formUrl);
req.ContentType = "application/x-www-form-urlencoded";
req.Method = "POST";
byte[] bytes = Encoding.ASCII.GetBytes(formParams);
req.ContentLength = bytes.Length;
using (Stream os = req.GetRequestStream())
{
	os.Write(bytes, 0, bytes.Length);
}
WebResponse resp = req.GetResponse();
cookieHeader = resp.Headers["Set-cookie"];

string pageSource;
string getUrl = "url";
WebRequest getRequest = WebRequest.Create(getUrl);
getRequest.Headers.Add("Cookie", cookieHeader);
WebResponse getResponse = getRequest.GetResponse();
using (StreamReader sr = new StreamReader(getResponse.GetResponseStream()))
{
	pageSource = sr.ReadToEnd();
}

using (StreamReader sr = new StreamReader(resp.GetResponseStream()))
{
	pageSource = sr.ReadToEnd();
}