I can't just do it for you; you need to read the instructions and edit and install the mod, using your specific category id's and other info. The instructions are as detailed as I can make them, and installation is very simple.

Do you have a file editor like Notepad++? You can download it free from sourceforge.net. You will also need something like winzip or 7zip to unzip the downloaded package, and an FTP program like Filezilla to send the /includes/ folder from your pc to your server. 7zip and Filezilla are also available from sourceforge.

You will need all of these things to maintain and upgrade your site in the future.