NGINX error - [emerg] "server" directive is not allowed here - nginx

Question

I just installed nginx for my lab, in accidentally i deleted default file in /etc/nginx/site-available, then i copy the configuration on the internet, but it can not work with the new config, can someone help explain me what the error ?
here is the error that i got
Nginx error
root#kali:/etc/nginx/sites-enabled# [emerg] "server" directive is not allowed here in /etc/nginx/sites-enabled/default:16^C
root#kali:/etc/nginx/sites-enabled# nginx -s reload
nginx: [emerg] "server" directive is not allowed here in /etc/nginx/sites-enabled/default:16
here is the default file in /etc/nginx/sites-available
server {
listen 80 default_server;
listen [::]:80 default_server;
# SSL configuration
#
# listen 443 ssl default_server;
# listen [::]:443 ssl default_server;
#
# Note: You should disable gzip for SSL traffic.
# See: https://bugs.debian.org/773332
#
# Read up on ssl_ciphers to ensure a secure configuration.
# See: https://bugs.debian.org/765782
#
# Self signed certs generated by the ssl-cert package
# Don't use them in a production server!
#
# include snippets/snakeoil.conf;
root /var/www/html;
# Add index.php to the list if you are using PHP
index index.html index.htm index.nginx-debian.html;
server_name _;
location / {
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
try_files $uri $uri/ =404;
# proxy_pass http://localhost:8080;
# proxy_http_version 1.1;
# proxy_set_header Upgrade $http_upgrade;
# proxy_set_header Connection 'upgrade';
# proxy_set_header Host $host;
# proxy_cache_bypass $http_upgrade;
}
# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
#
#location ~ \.php$ {
# include snippets/fastcgi-php.conf;
#
# # With php7.0-cgi alone:
# fastcgi_pass 127.0.0.1:9000;
# # With php7.0-fpm:
# fastcgi_pass unix:/run/php/php7.0-fpm.sock;
#}
# deny access to .htaccess files, if Apache's document root
# concurs with nginx's one
#
#location ~ /\.ht {
# deny all;
#}
}
# Virtual Host configuration for example.com
#
# You can move that to a different file under sites-available/ and symlink that
# to sites-enabled/ to enable it.
#
#server {
# listen 80;
# listen [::]:80;
#
# server_name example.com;
#
# root /var/www/example.com;
# index index.html;
#
# location / {
# try_files $uri $uri/ =404;
# }
#}

Answer 1

You might've to write this as below, server block comes inside http block.
http {
server {
// your rules
}
}
if you are including this virtual host as seperately in some other conf file. then you have to do below with default conf.
http {
server {
// your rules
}
include v.hosts/*.conf;
}