If you wish to add a new template to the template library for all users to access this article will give you instructions to do so.
First you must prepare and finalize your HTML template file. This is the HTML that will be loaded into the email editor when the template is selected for use.
Create a new folder with your template name and insert your html file into that folder. Name the file index.html
Create a preview file in gif format and call it preview.gif The image should be 247×200 pixels.
Place your folder via FTP here: admin/resources/email_templates/Basic
Basic is the name of the group of templates. You could create a new folder if you wish or you can place your new template within any existing folder.
That should do it!