Exporting a theme from your environment.
When moving a theme from one environment to another (such as from staging into production), the first step is to download the theme.
Open the Theme Designer (you can do this from any space)
Click the magnifying glass
This will appear to the right of the Installed Themes setting.
Select a theme for downloading
Click on the theme in the Available Themes list at the bottom of the window.
Click the download button