How to add PDFsharp lib in C#?

I am new to C#.net, I downloaded PDFsharp lib. But how to add this lib to our project?
My project is to create a PDF file. Please provide me step by step instructions. After unziping it has 32 folders.
I tried by coping it in my project folder, but same errors come.

"The type or namespace name 'PdfSharp' could not be found (are you missing a using directive or an assembly reference?)"