What's the correct way of creating a new Admincp screen?

[lagrangianpoint]

To be more specific,
Let's say I want to create a URL like:
/forum/admincp/mystatistics/
And be able to use vBulletin functions and core, as well as my own custom PHP includes.

Or in other situations, I want to create something like:
/forum/shoppingcart/
and use vBulleting functions, and my own functions.

Thank you