How to read yuv file in C# with filedialog?

How can add yuv file byte in byte a array?

private void button1_Click(object sender, EventArgs e)
{
    openFileDialog1.ShowDialog();
    textBox1.Text = openFileDialog1.FileName;
    label1.Text = openFileDialog1.SafeFileName;
    byte[] a = openFileDialog1.FileName;      
}