First download the patch file and unzip it. Then upload the files to your server. If a file is in a folder, then it goes to the corresponding folder when you upload it to your server. Then (step 4) run install/upgrade.php (you do this by entering
www.mysite.com/install/upgrade.php into your browser, using your own domain name of course).
When that's done, continue with step 5 (and post here if you need more help).