Domain Name Issue
The way I found the correct file to update was to look in the /path/to/nginx/conf.d/ file for different files. I don't remember what I saw, but I saw it reference something else that vestacp had created for me under /home/username/web. I went to those files and followed the path even more until I found the actual .conf for the domain I wanted to use and modified the config it had created for me to one that proxies the port. You would be correct that you have to edit a text configuration file, I used nano but I suppose you could use emacs.
When I get home from work I'll see if I can figure out for sure what I did. All I know is that once I found the conf.d folder I was able to trace my way up to the appropriate place.
@HolyPhoenix Hold on, did you have a bacon signature yesterday? I made bacon in the oven last night and damn it was crispy! Also, thanks for pointing me in the right direction.