How to include seperate .cs files?

I have an asp.net 2.0 app running on Win2003 server adn I have seperate .cs files that have methods that I call on. When I run the app on my development machine it runs fine, but on the server it doesn't see the seperate .cs files. Anyone know what I can do to fix this?

Compiler Error Message: CS0103: The name 'DataHandler' does not exist in the current context

How do I go about doing that?

I compiled the seperate .cs code files into a dll and added them as a reference into the project. Built it and it compiled sucessfully. When I ftp'd it up to the server, I still get the same error... CS0103: The name 'DataHandler' does not exist in the current context

Use these steps

Step1: Go to the Option Build ->Publish Site

Step2: Select the destination folder and copy that folder to development server

                                             OR

           if you are using FTP then give that path and copy that files to development server.

So that contains All necessary files to run the application not cs files and your application will work fine.