The first thing to do is to decompress the package into its constituent files. If you downloaded the .zip package and your computer is running a recent version of Windows® all the tools you need to do this are available as part of Windows®. This section will assume that you have downloaded the .zip package and that your computer is running Windows XP.
To extract the files from the package, open the folder on your computer where you saved the vBulletin package and right-click on its icon, then choose Extract All from the pop-up menu.


upload - This folder contains the vBulletin files that need to be uploaded to your web server.
You should now rename the 'upload' folder to match whatever name you gave to the directory containing your vBulletin files on your web server. In this example, the folder containing the vBulletin files is called 'forums'.
NOTE: If you have changed the names of the 'admincp' and 'modcp' directories in your config.php file, be sure to make the same change to these subdirectories prior to uploading.

- searchshell.php - This file will allow you to rebuild the search index.
- vb_backup.sh - This file will allow you to run a database backup via SSH/Telnet or a scheduled backup through cron.
- tools.php - This file must be uploaded to the admincp folder and allows you to perform certain tasks should your board go down or you accidentally lock yourself out of the Admin Control Panel. This file must be deleted immediately after use or it will cause a SEVERE security problem.
Note:
As you already have a vBulletin installation running on your web server, you should delete the install.php file in the install directory before you proceed to upload the files.
Note:
These instructions are for 3.5.0 and higher. If you are upgrading from vBulletin 3.0.x to 3.5.0, you will also need to recreate your includes/config.php file based on the new version of includes/config.php.new. Please see this page in the installation section on how to edit the config file. This step is not necessary for individual upgrades within the 3.0.x or 3.5.x series.
If you are upgrading from vBulletin 3.5.x to vBulletin 3.6.x you do not need to edit the config.php file.
If you are upgrading from vBulletin 3.5.x to vBulletin 3.6.x you do not need to edit the config.php file.

"Note:
As you already have a vBulletin installation running on your web server, you should delete the install.php file in the install directory before you proceed to upload the files."
It is unclear to me whether this refers to the install.php in the current installation or in the upgrade package.
[Editor's Note: It is referring to install.php in the newly downloaded files or upgrade package.]