Metabase welcome page for “as a service”

Environment:
Debian GNU/Linux
Bitnami LAMP stack + Metabase jar

How is the following code applied? Is it a stand-alone file or must it replace something in an existing configuration file?

server {
listen 80;
listen [::]:80;
server_name mymetabasedomain.com;
location / {
proxy_pass http://127.0.0.1:3000;
}
}

The most relevant file appears to be this 500+ line file:
~/opt/bitnami/apache2/conf/httpd.conf

Guide followed:

@mesquest The configuration snippet is for Nginx. You are using Apache.
You would have to follow an Apache tutorial, example this:
https://www.digitalocean.com/community/tutorials/how-to-use-apache-as-a-reverse-proxy-with-mod_proxy-on-debian-8