VB.NET Programmer-defined Classes

I'm a newbie in VB.net from Java.
I've tried to create .VB classes for my ASP.net web pages (in one
project). And they don't seem to communicate with my .aspx pages. Do I
have to compile thiz .vb classes to .dll before they're recognized by
aspx pages or maybe I should call/import them somehow <I also don't
know how>.

Also the Global.asax, seems to confuse me. How does it work,
especially when when you've got THREE Java Servlets to convert to ONE
global.asax?

Help???