Class library export question

In the old world of programming you use to write a dll that could be called
from most any type of application. Inside your dll you exported the
functions you wanted to have other programs be able to call and the ones you
didn't export you just let sit. However, I'm now trying to write a C# dll
(class library) that I can call from other applications, but I'm not sure
how to do this. Is there somewhere you need to export the function? Is
there some special way to make the call?

My test client app is a delphi application, but I get an access violation
just trying to run the app, so obviously there is a step I"m missing.

Thanks,

glenn