@bobbafett: If you have added child theme then it’s good and your changes will not be modified and also keep in track with the changelog http://catchthemes.com/changelogs/catch-box-theme/ . This will list the things that changes in various versions.
Now there is two option for custom css. One you can add it up in your child theme style.css this is best option but if you want the easy option then you can add it in “Custom CSS” box in your Theme Options panel
/* You can decrease the padding top for #main wrap */
#main { padding-top: 2em; }
/* For post title padding */
.entry-header hgroup .entry-title { padding-top: 15px; padding-bottom: 10px; }
/* For content below the title */
.entry-content, .entry-summary { padding-top: 2em; }
For adding files in child theme, it depends on which files you are changing it.