If you already have an Odoo server and restapi module installed, you just need to follow below steps
To use REST API on Odoo, you will need to set consumer key and secret for OAuth application on the user account you want to use:
- Log in your Odoo instance with an administrator account
- Go to Settings ‣ Users ‣ Users
- Click on the user you want to use for REST API access
- Click the OAuth applications button
- Register an Application you want to interact with your Odoo instance
- Click on Save button to generate Consumer Key and Secret.