There are several ways to embed texts and custom HTML on your Joomla site using the component & plugin JEmbedAll: you can use an iframe (only replace the URL with the one belonging to some script on server), showtext (for embedding into a span tag) and showdiv (for embedding into a div tag).
[ iframe = http://www.example.com/test.php ]
For the following JEmbedAll strings you have a form in the JEmbedAll configuration section (go to Joomla administrator / Components / JEmbedAll) to define the texts and to manage the list. They are meant to make your work easier: when you have to add the same text over and over again just add into the list and replace the "123" in the examples below with the ID of the text. For all the examples given: don't use them with spaces between the bracket [].
[ showtext = 123 ]
[ showdiv = 123 ]
You should use this JEmbedAll carefully in your website: the HTML tags inside them may break your template if there are divs not closed. In the administrator section you can edit this string - you can change its name and the CSS code attached. Using the CSS code you can set the width and height of the embedded part of the page, the position and other attributes (like the margins).