Bukkit

Go back the front page and click on the "Download" on the right-up corner, or click the "Files" tab on the top and select the version you want to download. There you can check the changelog too.

Put the jar file into you 'plugins' folder. Now if you start or reload your server it will be loaded and it will run.

Open up the 'Penalty' folder in your 'plugins' folder. If it does not exist create it. Make a 'penalties.yml' file. The easiest way to do that is to open notepad, write something and select 'Save As...' then select the file type to 'All files (*.*)' and write the name 'penalties.yml' to the file. Save. Now you have your penalties.yml file. Check this page to learn how to fill it. Here is an example too.

In the game use the following commands: