You simply click on "Options" in the top navigation bar, and click on "Send Invitation" in the drop down menu. From there, a "Send Email Invitation" dialogue box pops up, where you can fill in your email address in the From: field and any number of attendees in the To: field. Fill in a subject and message, and the invitation will be automatically emailed to your included recipients.
The other method of inviting attendees is to copy the session link location to your clipboard and paste it into an email using your personal email application. This is accomplished by clicking on "Options" as depicted in the screenshot above, selecting "Copy Session Link," and then clicking the "Copy" button on the dialogue box that pops up. This will copy the session link to your system's clipboard for cutting-and-pasting.