In this tutorial I create simple button shortcode with three attributes:

  • url
  • target
  • background

Put this code in your functions.php file

Wordpress 

function btn_big_shortcode( $atts, $content = null ){
	$args = shortcode_atts( array(
		'url'           => '',
		'target'        => 'self',
		'background'    => '#F39D77',
	), $atts );
	$out = '<div class="btn-big">
				<a style="background:'. esc_attr( $args['background'] ) .'" target='. esc_attr( $args['target'] ) .' href='. esc_attr( $args['url'] ) .'>
				'. do_shortcode( wp_kses_post( $content ) ) .'
				</a>
			</div>';
	return $out;
}
add_shortcode('btn_big', 'btn_big_shortcode');

By the same principle, you can add attributes to an array and display them in a shortcode.

Now set the CSS styles for the button

CSS 

.btn-big a {
    display: inline-block;
    font: bold 20px sans-serif;
    color: #fff;
    border-radius: 3px;
    padding: 10px 40px;
    margin-bottom: 15px;
    text-align: center;
    text-decoration: none;
}
.btn-big a:hover{
    text-decoration: none;
}

The button is ready, to output it add this shortcode in text editor:

[btn_big url="http://keksus.com/"]Sample button[/btn_big]

Only change the link to the one you need.
If you want open link in a new window, add the attribute target="_blank" to shortcode:

[btn_big url="http://keksus.com/" target="_blank"]Sample button[/btn_big]

If you want change button background color, add the attribute background="#000" to shortcode:

[btn_big url="http://keksus.com/" target="_blank" background="#000"]Sample button[/btn_big]

Demo

Sample button