If you want to store the data of an invoice, click the "Save" button. If you want to store a customer, click the "Save" button. If you need a useful answer, ask a proper question.

I would recommend reading this https://www.odoo.com/documentation/9.0/setup/install.html. 

You will need to configure Odoo to connect to a postgresql user. This can be done in the Odoo configuration file or through flags passed when you run odoo.py. Then everything is done through the database manager built into Odoo.