XCode 3

Ok so I'm having a little bit of difficulty working through this tutorial.  The problem is that the tutorial, and nearly all of the associated documentation about Objective-C, was created using XCode 2.  So when I am trying to follow along with XCode 3, there are many differences between the two.  The programs are basically the same, but I've found some large differences that make it difficult to follow along.  So much of my time is being spent trying to figure out how to do a task they describe in the tutorial a different way in XCode 3.  The first problem I encountered was with creating classes.  In the Interface Builder I had to create a ConverterController class that would connect the visual elements (Text fields, words, buttons, etc.) with the Converter class that would do the operation of actually converting the numbers and giving a result.  There is a simple Class window pane in XCode 2 that you select and then click on "New Class", this pane is not present in XCode 3.  I did manage to figure out how to create a new class in XCode 3, which has a Library of objects and you can select a generic NSObject from that and then define it further to create a new class.  I am now trying to figure out how to connect this class I have made with the interface that I created earlier, because the methods for doing this are different than the tutorial shows.