how to update bostan theme

I’m totally lost on how to update my theme, the documentation says the following…

Automatic Update

We strongly recommend updating the theme regularly to ensure recieving new features and fixes, and the theme settings won’t be overwritten, but any changes at theme files will be overwritten, so we recommend applying changes to a child theme.

To receive new updates for your theme, all you need to do is going to backup options in your Bostan Theme Options and fill your Themeforest username and API key, you can generate api from your theme forest [My settings] tab > [API KEYS] .

The problem is that I don’t see this any place to put a themeforest username and api key in the settings section. I also don’t see anything about a “child” theme?