Campaigner (in common with all of my ExpressionEngine add-ons) is no longer officially supported.
Check out the wiki for installation and usage instructions, and feel free to fork the repo if you'd like to make some changes or improvements (it's distributed under a liberal open source license).
Hopefully this will be everything you need to use this add-on in your projects, but if not please don't email me asking for support; I don't even have ExpressionEngine installed locally any more.
Campaigner makes it easy to subscribe members of your ExpressionEngine website to one or more Campaign Monitor mailing lists.
Whatever your ExpressionEngine membership preferences, and however you've configured your Campaign Monitor mailing lists, Campaigner just works, straight out the box. And that includes full support for many third-party add-ons.
Enter your Campaign Monitor API key, configure your mailing lists, and Campaigner does the rest. You'll be up and running in minutes.