While writing a new Post may seem like the most basic WordPress function, the interface can be rather intimidating at first, especially if there are added features turned on such as SEO or Social Media auto-posting, etc. WPBeginner.com has a great basic primer plus video that can be very helpful.
This article from covers all of the essentials with easy to follow explanations and screenshots.
Take some time to read through the article and watch the video - it will make setting up a new Post easier and faster.
Photo Credit: John Fischer