Edit the file /etc/netplan/50-cloud-init.yaml like the one below and just substitute the appropriate IP adddress, gateway and DNS servers for your environment.
network:
ethernets:
enp0s3:
dhcp4: no
addresses: [192.168.88.18/24]
gateway4: 192.168.88.1
nameservers:
addresses: [192.168.88.1,8.8.8.8]
version: 2
then do:
$ sudo netplan apply