Run this command with database name, you want to backup, to take dump of DB.
pg_dump -U {user-name} {source_db} -f {dumpfilename.sql}
eg. pg_dump -U postgres mydbname -f mydbnamedump.sql
Now scp this dump file to remote machine where you want to copy DB.
eg. scp mydbnamedump.sql user01@remotemachineip:~/some/folder/
On remote machine run following command in ~/some/folder to restore the DB.
psql -U {user-name} -d {desintation_db}-f {dumpfilename.sql}
eg. psql -U postgres -d mynewdb -f mydbnamedump.sql