http://www.cyberciti.biz/faq/install-nginx-centos-rhel-6-server-rpm-using-yum-command/

Step #1: Install nginx repo

# cd /tmp
# wget http://nginx.org/packages/centos/6/noarch/RPMS/nginx-release-centos-6-0.el6.ngx.noarch.rpm
# rpm -ivh nginx-release-centos-6-0.el6.ngx.noarch.rpm

Step #2: Install nginx web-server

# yum install nginx

Step #3: Turn on nginx service

# chkconfig nginx on

How do I start / stop / restart nginx web-server?

# service nginx start
# service nginx stop
# service nginx restart
# service nginx status
# service nginx reload

Step #4: Configuration files

1. Default configuration directory: /etc/nginx/
2. Default SSL and vhost config directory: /etc/nginx/conf.d/
3. Default log file directory: /var/log/nginx/
4. Default document root directory: /usr/share/nginx/html
5. Default configuration file: /etc/nginx/nginx.conf
6. Default server access log file: /var/log/nginx/access.log
7. Default server access log file: /var/log/nginx/error.log

To edit the nginx configuration file, enter:
# nano /etc/nginx/nginx.conf

Set or update worker_processes as follows (this must be set to CPU(s) in your system. Use the lscpu | grep ‘^CPU(s)’ command to list the number of CPUs in the server)

worker_processes  2;

Turn on gzip support:

gzip  on;

Edit the file /etc/nginx/conf.d/default.conf, enter:
# nano /etc/nginx/conf.d/default.conf
Set IP address and TCP port number:

    listen       199.241.137.179:80;

Set server name:

    server_name  vps.zhenglei.net;

Start the server:
# service nginx start
Verify that everything is working:
# netstat -tulpn | grep :80
# ps aux | grep nginx

Firewall configuration: Open TCP port # 80

Edit the file /etc/sysconfig/iptables, enter:
# nano /etc/sysconfig/iptables
Add the following lines, ensuring that they appear before the final LOG and DROP lines for the INPUT chain to open port 80:

 
-A INPUT -m state --state NEW -p tcp --dport 80 -j ACCEPT

Save and close the file. Finally, restart the firewall:
# service iptables restart