The idea of this tab is that non-tech people don't want to enter too many technical details, hence they have “textual” content to see in the first tab.
If you want to dig into the tech, two tabs can be used to do that.
In this tab, you can edit some global options with a nice UI
Change the options of Index.Rmd, _output.yml and _bookdown.yml just as if you were in any editor
Open an editor for any file contained in same directory as the index.Rmd.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.