importing file to Edit Themes

Hey,

I need to add two css files to the list of files shown on the right hand side of my Edit Themes menu (Appearance –> Edit). These files are not currently shown because, as it says in the stylesheet of my PlatformPro theme:

——————————-
Why isn’t the CSS in this file?
Two reasons: First, to seperate the theme description information and it’s formatting. Second, to prevent people from editing this file from the WordPress Admin only to find out later that those edits prevent them from upgrading.

*/

/* Get Core CSS */
@import url(‘core/css/core.css’);

/* Get Theme CSS */
@import url(‘css/theme.css’);
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So, how can I “import” these files? Thanks for helping a newb!