Web Server error on restart if adding required code to nginx.conf

Hi,

When I add the following code:

# BEGIN W3TC Page Cache core
set $w3tc_rewrite 1;
if ($request_method = POST) {
    set $w3tc_rewrite 0;
}
if ($query_string != "") {
    set $w3tc_rewrite 0;
}
if ($http_cookie ~* "(comment_author|wp\-postpass|wordpress_logged_in|wptouch_switch_toggle)") {
    set $w3tc_rewrite 0;
}
if ($http_user_agent ~* "(W3\ Total\ Cache)") {
    set $w3tc_rewrite 0;
}
set $w3tc_preview "";
if ($http_cookie ~* "(w3tc_preview)") {
    set $w3tc_preview _preview;
}
set $w3tc_enc "";
if ($http_accept_encoding ~ gzip) {
    set $w3tc_enc _gzip;
}
# END W3TC Page Cache core
# BEGIN W3TC Browser Cache
gzip on;
gzip_types text/css text/x-component application/x-javascript application/javascript text/javascript text/x-js text/richtext image/svg+xml text/plain text/xsd text/xsl text/xml image/bmp application/java application/msword application/vnd.ms-fontobject application/x-msdownload image/x-icon image/webp application/json application/vnd.ms-access video/webm application/vnd.ms-project application/x-font-otf application/vnd.ms-opentype application/vnd.oasis.opendocument.database application/vnd.oasis.opendocument.chart application/vnd.oasis.opendocument.formula application/vnd.oasis.opendocument.graphics application/vnd.oasis.opendocument.spreadsheet application/vnd.oasis.opendocument.text audio/ogg application/pdf application/vnd.ms-powerpoint application/x-shockwave-flash image/tiff application/x-font-ttf audio/wav application/vnd.ms-write application/font-woff application/font-woff2 application/vnd.ms-excel;
location ~ \.(css|htc|less|js|js2|js3|js4)$ {
    expires 31536000s;
    etag on;
    if_modified_since exact;
    add_header Pragma "public";
    add_header Cache-Control "public";
    add_header X-Powered-By "W3 Total Cache/0.9.7.2";
    try_files $uri $uri/ $uri.html /index.php?$args;
}
location ~ \.(html|htm|rtf|rtx|svg|txt|xsd|xsl|xml)$ {
    expires 3600s;
    etag on;
    if_modified_since exact;
    add_header Pragma "public";
    add_header Cache-Control "public";
    add_header X-Powered-By "W3 Total Cache/0.9.7.2";
    try_files $uri $uri/ $uri.html /index.php?$args;
}
location ~ \.(asf|asx|wax|wmv|wmx|avi|bmp|class|divx|doc|docx|eot|exe|gif|gz|gzip|ico|jpg|jpeg|jpe|webp|json|mdb|mid|midi|mov|qt|mp3|m4a|mp4|m4v|mpeg|mpg|mpe|webm|mpp|otf|_otf|odb|odc|odf|odg|odp|ods|odt|ogg|pdf|png|pot|pps|ppt|pptx|ra|ram|svg|svgz|swf|tar|tif|tiff|ttf|ttc|_ttf|wav|wma|wri|woff|woff2|xla|xls|xlsx|xlt|xlw|zip)$ {
    expires 31536000s;
    etag on;
    if_modified_since exact;
    add_header Pragma "public";
    add_header Cache-Control "public";
    add_header X-Powered-By "W3 Total Cache/0.9.7.2";
    add_header Link "<$scheme://$host$uri>; rel=\"canonical\"";
    if ($request_uri ~ ^[^?]*\.(ttf|ttc|otf|eot|woff|woff2|font.css)(\?|$)) {
        add_header Link "<$scheme://$host$uri>; rel=\"canonical\"";
        add_header Pragma "public";
        add_header Cache-Control "public";
        add_header X-Powered-By "W3 Total Cache/0.9.7.2";
        add_header Access-Control-Allow-Origin "*";
    }
    try_files $uri $uri/ $uri.html /index.php?$args;
}
add_header Referrer-Policy "";
# END W3TC Browser Cache

to /etc/nginx/nginx.conf

The service is not restating. it gives an error for each added line.

Feb 19 01:14:21 tnmc-web1 systemd[1]: Starting A high performance web server and a reverse proxy server...
Feb 19 01:14:21 tnmc-web1 nginx[27603]: nginx: [emerg] "set" directive is not allowed here in /etc/nginx/nginx.conf:90
Feb 19 01:14:21 tnmc-web1 nginx[27603]: nginx: configuration file /etc/nginx/nginx.conf test failed

The existing file content (before adding anything) is:

user www-data;
worker_processes auto;
pid /run/nginx.pid;

events {
	worker_connections 768;
	# multi_accept on;
}

http {
	# Basic Settings
	##
	client_max_body_size 120M;
	sendfile on;
	tcp_nopush on;
	tcp_nodelay on;
	keepalive_timeout 65;
	types_hash_max_size 2048;
	# server_tokens off;

	# server_names_hash_bucket_size 64;
	# server_name_in_redirect off;

	include /etc/nginx/mime.types;
	default_type application/octet-stream;

	##
	# SSL Settings
	##

	ssl_protocols TLSv1 TLSv1.1 TLSv1.2; # Dropping SSLv3, ref: POODLE
	ssl_prefer_server_ciphers on;

	##
	# Logging Settings
	##

	access_log /var/log/nginx/access.log;
	error_log /var/log/nginx/error.log;

# Enable Gzip compression
gzip          on;

# Compression level (1-9)
gzip_comp_level     7;

# Don't compress anything under 256 bytes
gzip_min_length     256;

# Compress output of these MIME-types
gzip_types
    application/atom+xml
    application/javascript
    application/json
    application/rss+xml
    application/vnd.ms-fontobject
    application/x-font-ttf
    application/x-javascript
    application/x-web-app-manifest+json
    application/xhtml+xml
    application/xml
    font/opentype
    image/svg+xml
    image/x-icon
    text/css
    text/plain
    text/javascript
    text/x-component;

# Disable gzip for bad browsers
gzip_disable  "MSIE [1-6]\.(?!.*SV1)";

	##
	# Virtual Host Configs
	##

	include /etc/nginx/conf.d/*.conf;
	include /etc/nginx/sites-enabled/*;

}