Lines can be added to your cover or spine design using the 'LINE' option shown on the tool bar under the shape section.
Drawing A Line
Click the 'LINE' icon and draw a line by clicking and dragging the mouse.
Line Colour
Select the line and change the line colour using the 'BORDER' option and 'FILL' option.
Line Width
Change the line width using the 'BORDER SIZE' option.
Drag the slider from 1 to 50, with 1 being the thinnest line and 50 being the thickest.
Duplicate Lines
Duplicate a line using the copy and paste options shown in the menu at the top of the Cover Design Tool panel.