DOMXML is the PHP 4 extension (obsoleted and replaced by the DOM extension in PHP 5). Meanwhile dl() is deprecated in PHP 5 (and basically gone in PHP 6; so you're a bit behind the times here).
However, as MarkR notes, there is no point trying to load a Windows DLL on what is clearly some breed of Unix; the right extension would more likely have a file extension of ".so".
To get you parsing XML, though, have a look at the [man]XML[/man] parser functions; they should be enabled already (as they need to be explicitly turned off).