1. Log in and select an event.
2. Along with "View," "Edit," and "Revisions" there is a tab above the content called "Registrations." Click Registrations.
3. On the next page is a list of all the people who have signed up to be reminded that the event is taking place. You can select individual users by checking off the box to the right of their email addresses. To select all users check the box in the top left corner next to "ID."
4. Above the list of emails, there is a box title "Operations." Select the "Send selected users an email" operation and click "Execute"
5. On the next screen fill out the "Subject" and "Message" fields like you would any other email.
6. Click "next" at the bottom of the page and then "Confirm" on the next page. This will send out the email to every user you checked off.