Newb question: How do i edit the config?

I'm trying to install phpBB and getting a "404 not found" install error. According to a thread on the subject, I have to edit my nginx config file by adding a couple of lines. It's at the bottom of the 1st post here:

https://area51.phpbb.com/phpBB/viewtopic.php?t=49426

However, when I add those lines to the bottom of my nginx.conf file, I get an error on reload saying:

"2018/11/28 16:20:42 [emerg] 36155#36155: "location" directive is not allowed here in /media/sdn1/MySiteName/.nginx/nginx.conf:28"

I'm sure I'm doing something wrong. Could anyone give any advice? I just plugged the code at the end of the file. Thank you.