Two quite different styles of programming in Morphic are available in Squeak 2.0: "Classic Morphic Programming" and "Scripting with Players".
(I) Classic Morphic Programming
This is the kind of programming for which Morphic was originally designed, and excellent examples of clean and attractive style using that approach can be found, for example, in BookPageSorterMorph and EnvelopeEditorMorph. Or Drag and Drop Explained which has the Plumbin example.
In "Classic Morphic Programming" style, you define your own subclasses of one or more generic Morph classes, and blend them into a working subsystem. Here, you're directly extending Morphic, in grand and time-honored Smalltalk manner. The fundamental tool here is the Browser: you locate and familiarize yourself with particular Morphic classes, and you then subclass the ones that you decide are appropriate for your application.
Most current Squeak users will prefer this traditional, mature, analytic, browser-based Smalltalk approach.