See An absolute beginner's guide to printing in .NET
Printing in .NET follows the overview of the print system quite closely. There are two main framework classes that you use to do all your work with printing, which are in the System.Drawing.Printing namespace: PageSettings, which is used for such things as selecting the paper size and page orientation, and PrintDocument, which is used to do the printing operation itself.
Arguably, the best way of implementing a custom print operation in .NET is to create your own class that holds a private variable that is of type PrintDocument and write the code to perform the printing in the event handlers of that class to print the desired document. I will discuss these in the order in which they occur in the life of a print operation.