This is an example of what a post looks like. It is just like a Page, except that there will be a time-stamp on it, and typically visitors are allowed to comment on the post. Once another post is published, this one will get pushed down on the page.
You can have separate paragraphs like this one. You can insert images, either from your computer, or ones that are already in your Media Library.
You can even link to other pieces of content of pages that are not on the site, like this link to Google.
As you get more and more posts, you can choose a category from the right side to keep them organized by topic for your visitors.