Making a ComboBox appear when a check box is filled in

I looked around and I saw some things related to java, but nothing for C#/WPF. What I'm trying to do is just what the questions says. For example if "Microsoft" is checked I want a Combobox to appear in the second panel, so that they can select "Windows", "Xbox" or what have you. Hope the question makes sense. I did some googling but I'm still really new at programming so I'm probably just missing something basic. I tried this

private void Microsoft_CheckStateChanged(object sender, EventArgs e)
    {
        comboBox_Copy.Enabled = (Microsoft.CheckState == 
  CheckState.Checked);
    }

But it says CheckState does not exist in the current context, as well as "combobox does not have a definition for enabled"

Thanks for the help!