#Open terminal or ssh (by any ssh client like putty.exe) and write the following:

sudo apt-get update -y

#install Postgresql database

apt-get install postgresql -y

# but if you need specific version like 10

sudo apt install wget ca-certificates

wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -

sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt/ bionic-pgdg main 10 -pgdg main" >> /etc/apt/sources.list.d/pgdg.list'

sudo  apt update

sudo apt-get install postgresql postgresql-contrib