How do you start a blog?

You can start a blog where you can promote your business or website. You can share all things on your blog which are related to your website or business. 

Firstly, you should ask yourself what are you writing and thinking and how can you help people if someone reads your blog?  If you are passionate about a subject and you have knowledge on that topic you should do some R&D on that particular topic and write something interesting on your blog. 

There are plenty of blogging websites like wordpress, tumblr, blogger etc where you can create your account and create a blog. In my opinion wordpress is the best blogging website.