Many people use a WordPress plugin to add their own shortcodes to posts, but there is (in my opinion) a far cleaner method to add custom short codes. This can be done by use of the WordPress functions.php file found in your themes directory.
I will give a quick demo of how to create a simple WordPress shortcode to format a page into separate boxes to hold some content.
First:
Open your functions.php file and add the function your shortcode is to preform.
'.$content.'
The function above will simply echo the content that is placed between the shortcode open and close tags in a div that can be styled to your liking in the style sheet. But first we need to add the shortcode hook to the functions.php that tells WordPress the name of the shortcode and it’s associated function:
add_shortcode("my_box", "my_box");
So the full function now looks like this:
'.$content.'
In the WordPress text editor you would now use this shortcode like this:
[my_box] Hello World, this is my content! [/my_box]
The resulting HTML would now look like this:
<div class="my_box">Hello World, this is my content!</div>