To find free blog host options, you can type in "free blog hosting" on your internet browser and scroll through. As of right now, there are two main blog hosts that most people seem to use: wordpress.com and blogspot.com. There are lots of opinions floating around as to which blog host is better but basically it boils down to this:
Wordpress allows for more customization. Blogspot (Blogger) is easier to use. Blogger is also owned by Google which some people prefer if they already use other Google programs.
Once you decide which free blog host to use, you're going to have to sign up by choosing a blog title and web address. My advice is to pick something catchy, try and include a key word in the title that will relate to the focus of your blog (like if it's a food blog try and use the word food or eating in the title) and try to pick words that are easy for people to spell/remember. You want to make your site easy to find and talk about.
After you set that up, you're going to have to do some legwork and spend time familiarizing yourself with the the layout. A lot of this is just getting used to where buttons are. If you've ever used Word or Power Point, you'll find a lot of the workings are self-explanatory. YouTube is a great resource if you find yourself confused. Just type in "how to use blogger" (or whatever you're using) and you'll get hundreds of introductory videos.