// Create Shortcode my_shortcode_button
// Shortcode: [my_shortcode_button color="blue"]

function create_my_shortcode_button_shortcode($atts) {
  
  // Attributes
  $atts = shortcode_atts(
    array(
      'color' => 'blue'
    ),
    $atts,
    'my_shortcode_button'
  );
  // Attributes in var
  $color = $atts['color'];

  // Your Code
}
add_shortcode('my_shortcode_button', 'create_my_shortcode_button_shortcode');