This is a simple netconfig for a static IP address on a Debian machine. In /etc/network/interfaces, replace your eth0 (or whatever) with this: 

auto eth0
iface eth0 inet static
    address 192.168.1.65    
    netmask 255.255.255.0
    gateway 192.168.1.251

Edit: I removed the network and broadcast statements because they are superfluous.