Hi @chilepower,
In the package that you downloaded from ThemeForest, you should have a “child-themes” folder containing the child themes, including the Gwangi Sensual child theme.
To install the child theme, we recommend that you take a look at the video at the end of this article of our documentation:
Installing Your Theme
Please note that before following that video, you should first zip the “gwangi-sensual” folder into “gwangi-sensual.zip” file to be able to install it.
Regards,