Hi,
A. To backup your database
    1. switch to postgres user
    sudo su - postgres
    2. backup with the ff command;
    pg_dump db_name > db_backup.sql
     [note db_name is the name of the database you want to backup; db_backup.sqlis the name you want to give your backup. Whatever name you want to give to your backup, end it with the .sql extension]
    3. To get the location of your backup, run this command from the terminal
    find / -name db_backup.sql 
B. 
    1. If your database is on a remote computer, connect to it using WinSCP;  supply your username and password
    2. browse to the directory where your backup is saved as gotten in step 3 of A above
     3. you can then copy the sql file to your desired location or download to a location on your local computer in case it is on         a remote computer.
I hope this helps a lot.