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?

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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