edit /etc/network/interfaces so it matches your network

auto eth0
iface eth0 inet static
address 192.168.68.205 - this is your ip
network 192.168.68.0
broadcast 192.168.68.255
netmask 255.255.255.0
gateway 192.168.68.200

then edit /etc/resolvconf/resolv.conf.d/base
nameserver <your router IP>