Change colour of textbox and restrict input

private void txtBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    // Validates integers n float
    if ((e.KeyChar > 47 && e.KeyChar < 58) || (e.KeyChar == 46) || (e.KeyChar == 8))
    {
      //Your logic here if needed
    }
    else
    {
      // Change the Color or show message 
      // MessageBox.Show("Please enter valid integer.");
    }
}