How to create a configuration file and use system.configuration dll in Visual Studio?

Question

I want to use the the System.Configuration dll for my application. So I made these actions:

1. Project > Add a new element > Add a Config file

But I couldn't find the .exe.config file in the list so I created a text file and put it in the same folder as the executable file (.exe) of my app and it worked. I could add it to my project.

2. Then I wanted to import the System.Configuration dll : Project > add a reference

And again I couldn't find the System.Configuration dll in the list so I used the NuGet install console and it worked!

`Install-Package System.Configuration.ConfigurationManager -Version 4.5.0`

My question is: why I can't find the Config file in my Visual C# Element Menu and I'm oblige to create a text document?

Thank you very much for your help. Clement