Missing References in References Manages "No items found" - WPF

Question

I need add in my WPF project on C# this code:

DialogResult result = MessageBox.Show(
        "Окрасить кнопку в красный цвет?",
        "Сообщение",
        MessageBoxButtons.YesNo);

But DialogResult isn't working. In the intenet, people tell, I need connect library System.Windows.Forms.dll, but in window "References Manages" show me: 'No Items Found'.

Next my step, I tried to look for package in NuGet, but I coldn't find. In the end I tried to download this package in the internet, but after install, I see a lot of errors.

I don't understand.

Screenshot settings project: