If you do not have a PostgreSQL database installed on your system, you will need to download the last line installation first.
Some of the little experiences when installing PostgreSQL:
The password provided at the time of installation (password) is for the ' Postgres ' account, which is a root-level level account. Please remember the username and password of this account, you need this user name and password every time you log in to PostgreSQL.
The default port for the PostgreSQL database server is 5432. If you want to modify the default port for PostgreSQL, you need to make sure that your new port does not conflict with the ports used by other services in the system.
Choose the locale that is the same as your location.
Do not run Stack Builder After the installation is complete.
Https://www.cwiki.us/display/CONFLUENCEWIKI/Database+Setup+for+PostgreSQL
Confluence 6 Installing PostgreSQL