You must double click on the .zip file in your Lang folder.
Then open the i18n folder and you will find the Dictionary.lang file.
Open it with Notepad ++
Make the necessary changes and then click save.
A window will open asking if you really want to save, click OK.
Your Lang file is ready to be used.
Here at this link [Only registered and activated users can see links. ] you have a list of the necessary entries to be included in the dictionary.