How to simply add a black horizontal line

Hi guys, your stuff is amazing.

I simply need to know how to add a horizontal line, as when I add one in Siteorigin editor, it doesn’t display or could possibly be displaying white as background is white.

Is there any way to force it to be black?

I am using the standard SPACIOUS theme. and bascially I want to do something that looks like this:

“Photo”
_______________________________________________

“Another Photo”

_______________________________________________

“Another Photo”

If I do Siteorigin Editor, and use the little horizontal lines tool, or do the alternate and press 4 hashes, it doesn’t display. Any ideas?

Cheers – Brian in Ireland