This guide will help you updating your current pluck installation (4.6 or 4.6.x) to the newest version of pluck (4.7). Updating from any version older than 4.6 is not suppported.
It is very important that you create a full backup of your pluck installation before proceeding with the updating procedure. Doing this may prevent a lot of trouble when the update doesn't work as expected.
First, you will have to download pluck from here. Unpack it on your hard disk. If you use Windows, you can use TUGZip to do this. A Linux-distribution is able to do it by default, without the need to install additional software.
Then, you'll have to upload all files to your pluck installation. Make sure your FTP-client overwrites all existing files, and keeps all other files intact.
Pluck 4.7 features an update script that will do the rest of the work for you. This script is located at docs/update.php. Before you can use this script however, you need to move it to the main directory of your pluck installation.
After moving the file, browse to your pluck installation and open it. Follow the on-screen instructions. Don't forget to delete update.php after the update!