When creating a blog you get paid by either selling your own products, services or by monetizing the blog using ads such as Adsense, Media.net content.ad or even selling your own ad space.
You need to create great content on your blog that gets ranked at the top of search engines and gain lots of website traffic before you start making good money using Adsense, Media.net or selling your own products or services.
You need to research topics and find highly searched keywords to write on that get a lot of search traffic and you need to give it a go for a minimum of 5 years before earning a significant amount of income through your blog.