Set up cookies for asp.net pages

I need to set up cookies for asp.net pages for specific page of a website. I have the PHP code but I don't know how should it look like in ASP.net and where I should put the code?

This is the PHP code:<?php
   $roi_data = $_GET\['roi'\];
   $hours = 6;
   $expire = time() * 60 * 60 * $hours;
   setcookie("bh_roi", $roi_data, $expire);
 ?>
 <html>
 <head>
 <title>My Sample Product Page</title>
 </head>
 <body>
 <\!-\- Product information would appear in this part of the page. \-->
 </body>  
 </html>

Thanks,
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