You can send emails from within any of your membership packages or your 'All members' view.
From the members listing page, select all members by clicking the check box next to the first name column or select individual members by selecting the check box next to each member. This will activate the email function on the right hand side:
Clicking 'Email' will bring up the below overlay:
Fill in your subject and text. If you would like the email to also go to unregistered members, be sure to select the 'Include unregistered' check box.