This can be achieved in graphical interface easily. But you have to familiar with command line, and it is easier to understand.
The configuration files regarding network are stored in /etc/sysconfig/network-scripts/
If you want to configure Ethernet 0 interface, look for the configuration file of "ifcfg-eth0"
open file using "vim" or "nano"
#vi /etc/sysconfig/network-scripts/ifcfg-eth0
As the figure show add those lines.................................
Another method of adding IP is DHCP server.....
you can configure same configuration file (ifcfg-eth0) to get IP from a dhcp server
open the above file using "vim" or " nano"
make following changes
BOOTPROTO=dhcp
and make following line as comment using "#" mark
#BROADCAST
#IPADD
#NETMASK
#GATEWAY
Every time you make changes your network, mind it to restart the network. it can be done according following method
You can restart everything (eth0, eth1, ppp0, etc) using
#service network restart
only eth0
#ifup eth0