As of current, the ability to export maps is limited to PNG image files. To export a map as a PNG, click on the download button in the lower right corner of the Map Layers window. 

Clicking this will pull open a new window. As you can see, in the near future we will be adding options to export maps in PDF files, or through embedding and social sharing. For now, a PNG file is all that is available. 

Click on the Download button to then download your map.