How to customize this shortcode which shows the number of views of a single post

Ah, that’s clever. You’re almost there:

function mywpp( $atts = NULL ) {
	extract( shortcode_atts( array(
		'id' => NULL,
		'range' => 'all'
	), $atts ) );

	$pID = NULL;

	if ( $id )
		$pID = $id;
	else
		$pID = get_the_ID();

	return '<div class="wppcounter">' . wpp_get_views($pID, $range) . '</div>';
}
add_shortcode('mwpp', 'mywpp');

I haven’t tested this, but it should work.

Let me know how it goes, alright?

Héctor, where were you? I missed you:-)
Thanks so much for your answer, but I have one problem with it:
When I put something like “This post has been viewd [mwpp id=”71″ range=”X”] times.” in post/page editor, I get the following output:

This post has been viewed
X
times.

In other words, the counter is displayed in a new line. To fix this, I put
display:inline!important; in the wppcounter class, but it didn’t work. could you please help me solve this problem?
By the way, the default value that you have specified for the range, is all, right?

Been too busy with work projects. At my job, we were short of personnel for a bit too much time and many projects got delayed – hence the load of work got too big and you know how that ends. I still have a lot to do (and will get even more work in the upcoming days) but decided to take this weekend to work a little bit on the plugin.

Anyways, do you really need to use a DIV element in there? How about this:

function mywpp( $atts = NULL ) {
	extract( shortcode_atts( array(
		'id' => NULL,
		'range' => 'all'
	), $atts ) );

	$pID = NULL;

	if ( $id )
		$pID = $id;
	else
		$pID = get_the_ID();

	return '<span class="wppcounter">' . wpp_get_views($pID, $range) . '</span>';
}
add_shortcode('mwpp', 'mywpp');

By the way, the default value that you have specified for the range, is all, right?

Yes, that’s correct. Also the post ID will default to the current post/page ID as well if you don’t pass it to the shortcode, so you could just use [mwpp].

Thanks again for your reply. Everything is ok now so I’m marking the topic as resolved.
By the way, I wish you success in your job and of course, your life.