Odoo allows you to add custom fields to the model if you are in debug mode. Click on Settings and then, in the Database Structure sub-menu, choose Models. You will get a list of all the models that make up your current Odoo installation, as shown in the following screenshot:
Using the standard search tools in Odoo that you have learned about so far, you can now limit the results to just show the sale.order model:
You can now click the sale.order model to open up the model and display all the ...