The obvious solution for inline literal inclusion is:
[source, html]
----
<div> xxxx </div>
----
(or instead of 'html' you might want 'php', or just use nothing if you don't have a syntax colouriser enabled).
To include from another file, you can do as in
this file (look for the 'source' blocks).
You can do inclusion of parts of files as well,
see the manual.
Hope this helps.