How do I locate the HTML in Shopify Liquid for editing a page layout?

[DevCanaan]

Hey everyone, I am running into some trouble and would like some assistance. I am a developer with knowledge of HTML, CSS, JS, and some Liquid knowledge. I am currently editing some code on the backend in the .liquid files and I can't find out how to locate the files I am looking for. 

I am trying to get rid of this open white space on product pages below a dropdown FAQ menu. It takes up a lot of space, especially on mobile. The only problem is that even though I know what I could do if it were an HTML file, I don't know where to find it in the files / liquid files. 

My thought was to make the menu a div itself, and then put all of the info in a separate div under it instead of beside it so the white space would be eliminated. I just can't seem to find where this information is stored. 

Thank you for any help you have to offer!