How can I create newsletter template by Simplenews I have Drupal v7 and installed the Simplenews module, but now when I send a newsletter, I need to edit the HTML format.

Where can I edit this template?
from this tutorial website I found after a quick google search:
http://www.wdtutorials.com/2012/07/06/drupal-7-how-create-newsletters-simplenews#.VCEqY_l_uVM


Using templates
First select the theme you like to use to render the emails in


/#overlay=admin/config/system/mailsystem



There are 4 template files you can override in sites/all/modules/simplenews/theme:


simplenews-block.tpl.php
simplenews-multi-block.tpl.php
simplenews-newsletter-body.tpl.php
simplenews-newsletter-footer.tpl.php


Just copy them to your theme templates folder (like themes/bartik/templates) and edit them.