The very first thing you do is to determine if you will be writing a page or a post. To help you understand the difference, this is my simplified way to tell the difference: Pages are usually non-interactive whereby posts are commonly interactive.
A page doesn’t generally offer the option of site visitor interaction, whereby a blog post does by means of providing people the option of interacting with you and other readers by writing their comments about the topic of your post. The idea behind blogging (as I understand it) is to get a topic of conversation rolling which begins with your blog post and continues by allowing your site visitors to respond by means of the comment box.
Not always, but most often a post will provide a comment box at the end of it for your site visitors to write their own comments (resembling my example on the right) and a page doesn’t usually have this feature. Some WordPress sites are blogs or contain blogs within them and some do not use blog posts at all. Just because you have a website built on WordPress does not mean you automatically have blogging capability.
Page and Post Link Navigation
Pages will be visible on your main site navigation by default of the WordPress system (unless you choose to not have a page(s) be displayed) and posts are usually found on what’s called the “sidebar” but this isn’t set in stone. The sidebar is what you normally see running vertically along the left, right or both sides of a website and can contain any number of things that you want your visitors to see and/or have easy access to. These locations can also be a mixture of both or even reversed because it isn’t set in stone. I’m just giving you the most common use.
This is a pretty simplified description of the difference between a page and a post. Hopefully, it’s enough to help you make your determination.