Where to paste code for redirecting a specific page

It depends on your theme. Try the functions.php file or the header.php?

Hmm, I tried pasting it into functions.php but that redirects the entire site to another page. How can I only have this code apply to a single page (the download page) on my site? Thanks

assuming your page slug is ‘downloads’…

if (is_page('downloads')) {
   if(is_ie() && get_browser_version() <= 8) {
      wp_redirect('https://www.example.com/update-your-browser/', 301);
      exit;
   }
}