Use your text editor to open the template and for creating CSS documents.

Windows Notepad or Wordpad are basic text editors. Any other text editor you are comfortable with is fine also.

There are many free text editors available to download on the web. Just type free text editor into your search engine to find many to choose from.

My favorite is NoteTab Light. While it is not a wysiwyg application, it does eliminate some of the tedium of coding through autocomplete libraries.