My own error page

Hi,
the topic is "how to link to my own error 404 page?"

I know, this subject certainly has been postet but I can't find any topic about.
On the internet I find some Joomla! error page changings for the error.php but not for a Website with WARP 7
The reason is, I do have an own error 404 page but do not know how to change the warp/layouts/error.php to link to my own page!

The page is: www.lanzarote-virtual.com/index.php?opti...cle&id=91&Itemid=337

I need help: Please tell me how to change the error.php in warp 7
Thank you!
Pedro

yootheme.com/support/warp/joomla/error-pages