Where can I download the sample package???

Hi all:
I want to write my own elements, where can I download the sample package???
I saw sample package with README start with:

*A SAMPLE PACKAGE
================

    Click supports dynamically linked 'packages' containing extra elements.
The two drivers -- specifically, the 'click' user-level driver and the
'click-install' program for the Linux kernel driver -- automatically link
with whatever packages are mentioned in a configuration's 'require'
statements. If you are building a collection of your own elements, it may
make sense to compile that collection as a package. Then you can keep your*

*Click sources separate from your package sources.*

but I don't know how to get it.

Best Wishes
gene