How to: Creating a Decision Tree like C# application.

Question

HI Guys

Ive been tasked with writting a project that will in turn be used as a dll for another project. The project or rather the code is based on a decision tree, and will produce different pdf letters as output based on certain conditions. NOw first off, has anyone ever written or knows how to write a C# application  that mimicks a decision tree, second, how do i generate pdf documents from c# code. And once that is all done, how will i then convert the project into a ddll such that the methods i write in the project will become visible in the main project that will use the resultant dll. I dont know if im making sense but please help me out.