Nothing to do with VB
or anything else relevant to ASP.NET or the .NET framework.
You just have to declare the field in the table as IDENTITY when you create (or modify) the table.
CREATE TABLE foo
id INT IDENTITY PRIMARY KEY,
If you don't use SQL to create your tables, then look at the tool you are using to create/modify your tables and figure out what it needs you do to tell it that you want in IDENTITY column.