There are some pretty good resources and tutorials on the main Eclipse and IBM's site. One of the best ways is to pick an open source plug-in that has some similar features to what you want to do and start to dissect it.
Eclipse has a pretty good "Your First Plug-in" tutorial. If it is confusing, I'm sure they would greatly appreciate your feedback. Keep in mind that Eclipse is essentially Java, so if you don't have a good grasp of Java go for general Java tutorials first, and then come back to Eclipse development.
They not only go through the simple code examples, but give you screen shots of the process since a lot of work is done through wizard type interface windows.
If these aren't helpful, perhaps you could be more specific as to what is difficult to follow.
I think a very good resource is also to look at the examples that are available via the new Plug-In Project wizard.
Depending on what you want to provide with your plug-in, you can choose from editor plug-ins, view plug-ins, plug-ins that provide a property page (just to name a few) and see how they're built and what extension points they implement.
