You can easily Add Horizontal Lines in the Text and Image Editor. You can also click on Left menu, click Elements, click Buttons and Shapes and drag-and-drop the element to the blue placeholder on the page and the Horizontal Line Properties menu will appear on the right.

In the Text and Image editor position the cursor where you wish to have the Horizontal Line and click on the  icon from the toolbar on the right. A placeholder will indicate the Horizontal Line positioning within your page content.

With the default settings you can change the Line Style and Ornament.

Style - it can be Single Line, Double Line, Dotted Line, Dashed Line, Fading Lines and Custom lines. Here are a few examples:

Ornament - you are able to select different pre-made ornaments for your Horizontal Lines, or have custom caption text. You can find few of these options displayed below:

Enable the Advanced Options from Site Settings to adjust the Ornament Alignment (Left, Center, Right), and the top and bottom Padding Around the Line.