How to update the Goodnews Theme?

I am working with Wordpress 4.5.3 and Goodnews 5.1.1.

How can I update the Goodnews Theme to its latest version, that is: Goodnews 5.8.3.
There is no “update” button or anything of the kind in Wordpress.
Is there a special plugin needed to update the theme?



Probably best to contact the theme owner through their support forums:

Thanks a lot. Regards.