The Decker Guided Tour includes some simple examples with explanations, as does the Decker Reference Manual. The Decker Reference manual includes descriptions of all the "interfaces" Decker provides for interacting with decks, widgets, and other goodies.
There are also a number of examples and walkthroughs in threads on this forum, like this thread where I walk through several approaches for implementing an adventure game inventory system.
If there's something in particular you'd like help with, feel free to post more specific questions!
