Enable Page Editor on any page that you wish to add a "Subscribe box" for users to join the list. Click plus sign in the desired area to bring up the Add Block dialog window. Select "Subscribe" in hte Standard Blocks. See the below image.

In Promotion > Email Campaign you could create an email campaign and send newsletters to your subscribers. Click "Add Email Campaign" button. Enter the email detail in the form and click "Add" button after you are done. You should see the email campaign that you just created. Click "Send" or "Send To Mailing List" button on the right to send email to the targeted list. "Send" button allows you to send test email to yourself or to any single email address. "Send To Mailing List" has the precompiled mailing lists from your site. "News Letter" contains the list that is collected via Create Newsletter Subscription.