How does one access a control from a static method?

Question

I have an application in C# .NET which has a MainForm and a few classes.

One of these classes receives incoming data messages from a network. I need to

Answer 1

private void FormMain_Load(object sender, EventArgs e)
{
    TheIncomingDataClass.SetupControl(textBox1);
}

public class TheIncomingDataClass
{
    public static TextBox textbox = new TextBox();
    public static void SetupControl(TextBox txt)
    {
        textbox = txt;
    }
    public void IncomingMessage(string message)
    {
        textbox.Text = message;
    }
}