If you are interested in learning how to use Dynamo, I would suggest starting at the Dynamo website. They have taken the time to create some worthwhile learning materials:

Dynamo Primer. This is a step-by-step introduction to Dynamo and its main concepts. It is fairly basic, but is particularly useful for new users.

Dynamo Video Tutorials. There are videos that accompany the Primer and additional Tutorials (though these are architectural-focused).

Dynamo Forum. A great resource. I frequently search through the topics and often find relevant answers. And if not, you can also post your own question.

Additional Resources
In addition to my Dynamo Posts, here are a few more resources that might be helpful.

Revit Dynamite and Ammo. by Jostein Olsen. This is one of the most interesting (and landscape-applicable) blogs I have found on Dynamo and Revit.

List of Dynamo Learning Resources on Revit Forum. A compilation of various blogs, tutorials, and various other Dynamo resources, by amoursol.