[Tu Tran]

Hi,

Yes, you can customize that on these files bellow:

app\locale\en_US\template\email\account_new_confirmation.html
app\locale\en_US\template\email\account_new_confirmed.html

And please try to refer the links bellow:

http://stackoverflow.com/questions/9249878/where-are-all-the-magento-email-templates-located
https://www.yireo.com/tutorials/magento/magento-theming/1670-customizing-magento-email-templates
http://www.templatemonster.com/help/magento-how-to-edit-store-emails.html