使用php和curl进行网络钓鱼演示

I have created a phishing site (for demonstration) that is identical to the login of the site that I am trying to copy. When you submit your username and password, it uses php to save them in a mysql database. Right now, it just redirects you to an error page (that I created) after it saves the info. I was thinking, to make this site more advanced, I could use the login data I saved and redirect people to the real site ALREADY LOGGED IN so its as if my site was the real one and nobody would know. I did some researching and found cURL but Im still not entirely sure how to use it in my case. I want to redirect people to the real site and log them in with the info they typed in on my phishing site. Thanks in advance!