How would I check for errors. If a person enters an incorrect name or doesnt spell it correctly I would like for a messagebox.show to display a message stating "Incorrect name or spelling" 

```
private void button1_Click(object sender, EventArgs e)
    {
        String Andrea;
        String Brittany;
        String Eric;
        if (textBox1.Text == ("Andrea"))
            Commission.Text = (Convert.ToDouble(textBox2.Text) / 10).ToString();
        if (textBox1.Text == ("Brittany"))
            Commission.Text = (Convert.ToDouble(textBox2.Text) / 10).ToString();
        if (textBox1.Text ==("Eric"))
            Commission.Text = (Convert.ToDouble(textBox2.Text) / 10).ToString();

        {

        } 

    }

```