XF 1.4 Duplication

The community I help manage has a custom theme on the site, it is based off the quark template and style, with permission. I need to know how to make a copy of the files/theme. I want to make variations of it. For example we have a light and dark theme. We how ever want to make some dark green, dark blue and other color themes. Also themes for donators and server administrators. I just need to know how to make a copy of the theme, so I can start messing with the colors and seeing what works. Do I export, change name and re import? Thank You
Thank you for taking time to reply. I read the article and still do not understand how to make a child of a template. I click create new style up top, and assign the PSdark as the parent, and nothing works. I go into the style and its blank. Nothing was copied over for me to start working.

I click on "Customize Style Components" and I get a error message of "This style contains no customized templates or style properties." The other child has all of its components. So what am I doing wrong?
I do not want to have to start from scratch lol. I want to be able to copy everything from the PartyServer Light or Dark style and just go in and tweek the colors. I want the page_container for example or the extra.css to stay the same. Can I give someone access and show you what I mean. Do you have another more detailed guide I can read? I do not know if I am even making the child right. Would screenshots help?