reference a class library in app code of an asp.net website

I have an asp.net website with a reference to a class libr开发者_开发知识库ary. I can reference the class library in the aspx pages but how do I configure my site so that I can also reference the class library from a .cs file in app code?

If you have the reference in your project, you should be able to just add some using clauses to the top of your .cs files to import the code libraries

EDIT: you will need to add a using clause for the namespace of the library, not your project