Problem Overriding Class Methods

[prc11]

At http://www.contao.org/overriding-class-methods.html it says to create a new xcustom/ModuleMyNavigation.php file and define the custom class ModuleMyNavigation.

Where does this file go? I assumed that xcustom was just a generic name, and I tried creating a new folder, so it looked like this:

system/modules/myCustomClass/myCustomClass.php
system/modules/myCustomClass/config/config.php

That didn't work. There aren't any error messages, it is just like the files don't exist.

Where should I put the files?

Thanks

[ramjet]

I believe the name of your module folder "myCustomClass" needs to come alphabetically after the module you are modifying (hence the use of x in the modules name often)
eg: a module called myCustomClass cannot modify anything in a module called "news", as m is before n.