Bulk email How-To's
Sending a bulk email to the users of your site is a two-step process: First you use CBMailing (Joomla->Components->CBMailing->Send mailing) to select the users to receive the email and to export this list of users to PHPList, which is the program that actually sends the mail.
Once you have exported the list to PHPList, you open PHPList, which is found at yoururl/lists/admin (e.g. http://hrtemplate.org/lists/admin). In PHPList you can compose your message; send yourself a test copy of the message to see what it looks like; and schedule the bulk mailing to your entire list.
You will find detailed instructions for all of this in the links below.