>>>UPDATE: I realized that "MyDataSet" is not a method name but a type returned by the method.
>>
>>Does the update mean that you got your code to compile?
>
>No. Just wanted to let you know that I mistyped. But still no success.
>
>If you look at the message Bonnie sent me, where she defined the three classes (I wish I could point to the message number here, if you don't find let me know). Look at her class CustomerAccess where she has
>public MyDataSet GetCustomer(long CustomerKey)
>
>You think she might have mistyped and meant there the "DataSet"?
>
>Thank you.

No I think Bonnie mean MyDataSet. DataSet is a generic dataset, MyDataSet is a typed-dataset. What I mean by a typed dataset is that the dataset is pre-defined, all the tables and all the columns in the tables are pre-defined.
If you add a new item to your project and select dataset you can either drag the customer table from the server explorer to the design surface or you can add your customer table by hand and then add columns to the table.

Now you could also just return a generic dataset, i.e. change MyDataSet to DataSet, but I would reccomend using typed datasets.

Please let me know if you want me to explain further.