How do I add a reference to an assembly?

I a开发者_开发知识库m trying to run some PDF to text C# code. I have references to 2 DLLs and I get this error when I try to run the program:

the type 'java.io.File' is defined in an assembly that is not referenced.
You must add a reference to assembly 'IKVM.GNU.Classpath,
Version=0.20.0.0, Culture=neutral, PublicKeyToken=13235d27fcbfff58'.

How do I add a reference to this assembly?

It seems that you are using an assembly that has been generated from a JAR file using the ikvmc compiler. You will need to reference the IKVM.GNU.Classpath assembly which is part of the IKVM project. Right click on References and then Add Reference... and pick the IKVM.GNU.Classpath.dll file.