Apparently (at least according to https://wiki.oxwall.com/install:manual_installation) the third step in the installation procedure for Oxwall 1.8.4 should show me a block of text that I should paste in ow_includes/config.php.
However on my fresh install (site hosted by Bluehost, php 5.6 installed) it doesn't show, even though the text is present in the page's html. This could be due to the fact that its containter (html > body > div.wrapper > div.body_wrapper > div.body > div.content > form > div) has its style set to display:none. When I change that to display:inline everything shows fine.