Why should you make use of the H tags in blog posts?
Because, in addition to the SEO benefits they bring, they highlight a roadmap through your article.
People skim read articles online, and if your article is just a load of unbroken text you'll lose them before the 4th line.
Reading unbroken text on the printed page is tough. Reading it online tougher.
Why Break Up Your Articles?
There are countless articles, on this site as well as others, explaining why you should break up your text into bullet points, sub headers and bolded portions.
If you do it properly, your readers should be able to read those highlighted bits and get the message.
There are so many articles (on everything) online now, that people reading an article on your blog for the first time will almost certainly have read articles on the same subject elsewhere.
What they really need, therefore, are the bits that are new and unique to your blog.
And breaking up your article into sub-headers and bullet points will help them to find those bits, which they can then dive into in more detail.
That will improve the reader-friendliness of your blog, which will increase the chances of them returning in the future.
What tools you can use to provide a roadmap through your article?
H tags, bolding, bullets, italics and font colour.
And H tags, bolding and italics are all things that indicate important bits of information to the search engines through their tags. So, provided you emphasise the right things, they'll improve your on-page SEO.
How do I Use These Tags?
In WordPress (and most blogging platforms) using these tags is supremely easy - even if you don't know what an H tag is.
All you need to do is use the styling commands in the Visual view tool bars and your blogging platform will do the rest.
If you're using WordPress, the default installation gives you one toolbar in the Visual view.
If you go to the New Post Add screen and roll your mouse over the buttons on that tool bar, you'll find one that says 'Show/Hide Kitchen Sink'. It's the last one on the bar:
Click that button and WordPress will display a second toolbar (as in the image above).
The first button on the second tool bar is a drop down menu with 'Paragraph' in the display box. Clicking that menu will drop down a list of Headings (Heading 1, Heading 2, etc).
Applying one of those Headings to your text will turn it into a sub-heading (your post title is the main heading) and apply the relevant H tag.
It's no different from using the Headings feature in Word.
Your post title will (should) be an H1, and you only want one H1 tag per article. So using Heading 2 and onwards for sub-headings throughout your article will give it a logical, search-engine-friendly H tag structure.
Good for on-page SEO, and good for reader-friendliness.