From the Email Editor, click on the "Test" icon on the far left-hand side. After selecting this icon, a "Send a Test" modal will open, and you can enter your email, plus four more. From the "Send a Test" modal, add in your email and select the "OK" button.
Email tests come from email@example.com and firstname.lastname@example.org, so you should mark this email off as "Not Spam," i.e., whitelist this email. Because you will continue to test emails, this will speed up the process and avoid any spam filters from being triggered while you are in the testing phase.
Another area you can send a test email is from the "Schedule Email Modal." Select the "Sent Test" button, add in your email(s) and select "OK."