Good question! The editor in your account is our 3GE email editor. At this time in the insert drop down there is only a greeting tag, but we do plan on including more to that in the future.
This thread in the Community has information on how to insert contact details. Please keep in mind that it will not work for custom fields. We also recommend setting up a test list to do a live send before your final send to make sure everything appears as it should. Any spaces or extra punctuation would break the workarounds, and it will not display in just a preview/test email.
If you have any specific things you'd like to see included in the Insert drop down menu, or other feedback we'd love to hear it! You can let us know exactly what you're looking for in future iterations of our editor by posting in our Editor Feedback Board.
I hope that helps, but please let us know if you have any other questions. Thank you!