Managing large code

Question

I am developing a VB.Net app using VS 2010. The app will generate a lot of code and I do not want a long log code-behind file. A few years back I did a C++ development and I could use "Include" statement to bring in code kept in separate files. That is not available in VB.Net. I have looked at Codefile and Module but little joy. Maybe I am missing something. Any assistance? I am new to VB.Net. Thanks.