Check out this 'how to' Tutorial that will teach you how to add a main image to your blog and how to add an image to the body of your blog text. This article also has a few great resources for free images that you can use to spice up your blog post or marketing designs.
Get the Do's and Don't's of blogging. This will get you started with how to have a successful blog. This is not a comprehensive list by any means, this is a place to start so you don't need to be 'scared' of saying the wrong thing.