Hello @kartik,
You just need to configure the Django settings before you do any calls, including importing your models. Something like this:
from django.conf import settings
settings.configure(
    DATABASE_ENGINE = 'postgresql_psycopg2',
    DATABASE_NAME = 'db_name',
    DATABASE_USER = 'db_user',
    DATABASE_PASSWORD = 'db_pass',
    DATABASE_HOST = 'localhost',
    DATABASE_PORT = '5432',
    TIME_ZONE = 'America/New_York',
)
Again, be sure to run that code before running, e.g.:
from your_app.models import *
Then just use the DB API as usual.
Thank You!