sudo pico /etc/network/interfaces
If your device name is eth0, the configuration block should look like the following-

iface eth0 inet static
address 192.168.1.110
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
dns-nameservers 208.67.222.222 208.67.220.220 127.0.0.1

If you wish to add another I.P. address, you can add a block similar to this-

iface eth0:1 inet static
address 192.168.1.111
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1

All that is needed now is a restart of networking-

sudo /etc/init.d/networking restart