How to create custom config section in app.config?

I want to add a custom configuration section in my app.config file. Is there a way to do it and how can I access these settings in my program. Following is the config section I want to add to my app.config:

<RegisterCompanies>
    <Companies>
      <Company name="Tata Motors" code="Tata"/>
      <Company name="Honda Motors" code="Honda"/>
    </Companies>
</RegisterCompanies>