I want to create a gadget for my blog that shows the Apple RSS Feed. How do I do this?
If you want to create a new gadget, please see the documentation on how to do this and then come back to Stack Overflow when you have a more directed question. It's hard for us to help you much with such a broad question.
However, it sounds like you just want a gadget that displays a particular RSS feed. In this case you just need to use the RSS Feed gadget that's already included in Blogger. Just go in to configure your site, add a gadget to the sidebar or wherever you want it, and then specify the gadget to be the RSS Feed gadget. You can then customize the gadget to point to a particular RSS feed, in this case the Apple one you want.