How to capture Pop-up window in WebBrowser in c#

Question

Hi,

   I am developing a Tool that want to open a webpage, login into that, Click Create issue button, when the button clicks the new Pop-up window is opening. i The tool want to fill the details by it self. then it should click the submit button. 

   

  I complete untill click the create issue button. I am using the WebBrowser. i capture the html code using Webbrowser.Document. Now my problem is, i cant get the Pop-up window code. That's a issue feed Window. I don't know how to get that code in webbrowser.Document. can any one help me. 

 

I am using c#. 

 

Thankz in Advance.