Custom Config Section Property C#

Question

I would like to configure custom in my app.config. How do i achieve this? This is C# console applications.

can you help on this ?

<Configurations>
    <ApiSettings>
        <BaseUrl>http://localhost:62954</BaseUrl>
        <EndPoint>api/token</EndPoint>
        <PollingIntervalInSeconds>10</PollingIntervalInSeconds>
    </ApiSettings>
</Configurations>

I'm getting below exceptions.