The Space element allows you to add a space between 2 sections of your newsletter. Select the Space element from the template library and drag & drop onto your newsletter. 

You can click anywhere in that element to format the colour, the the height and the width of the space.

Example  1. 

2 newsletter element without a space

Example 2: 

2 newsletter elements with a space in between, to which a background colour has been applied and the height reduced.