I’d rather see anyone making changes in a child theme instead of the parent theme but Quick and Dirty? Backup early and often but HERE is what I do…
Find that <Body tag and follow it until you find the closing ‘>’ or sometimes ‘/>’. Right after that type the word ‘HERE’. Save your work, revisit the site, and you’ll probably see the page with the word ‘HERE’ toward the top. If it’s not where you want to add a new piece of code then move it down past the next tag and the next… until you find that right spot.
Keep in mind the right spot might be in the header or footer files instead of in the page you are working with or even inside another included file.
Adding the word ‘HERE’ might break your style or something so don’t be afraid to drop the word inside of the next ‘<div>’ tag to maintain some semblance of the original layout.
Sometimes a <BR> added after ‘HERE’ will help also.
Once you find that right spot drop your new HTML in there overwriting that word ‘HERE’. If you mess up something it’s usually easy enough to delete that one-word change or your brand new code to get back to where you started.
I usually add a ‘remark’ above and below any changes I made. I’m 66 years old so I forget things otherwise. Your mileage may vary.
I really stink at design elements and such so I need to use tricks like this to help me. Hope this helps you, too.
When you’ve finished your ‘Quick and Dirty’ fix make yourself a sticky note to create a child theme and move or copy your modified code over to there. That way a future theme upgrade won’t clobber your changes.
There are others here who are very good at this stuff… but I figured I’d answer in the name of expediency.