To Create a blog post, its pretty easy. The hard part is coming up with the idea. Think about what you want to talk about. It could be a great resource you found on the web, a neat idea you use in class, a story from your teaching past, you choose. Remember to at labels to tag your posts.
Remember you can add images by uploading them or using a web URL.
You can also add video right on the blog (hopefully you can do the math better than Patricia Heaton does in this video)