At this point your blog is using the default theme that WordPress chose for it and it may not be exactly what you want. Don't worry, there are thousands and thousands of themes to choose from and there are also ways to tweak the appearance and function of themes once you find one that you like.
On the left navigation click "Appearance" (it's near the bottom). You should see a theme or two, including the one that you are using. Just for fun, let's install a new random theme from the Internet. Click the Install Themes button and then clicked "Featured".
You should see snapshots of a few themes. Click "Newest" to see several more. Pick one and install and activate it. [footnote] note, you may have to enter your FTP credentials; ie. username and password.[/footnote]
Once the theme is successfully installed, right-click on the name of your site [footnote] in the upper left corner right next to the big W, and Open Link in new tab.[/footnote]
This will open the published version of your site. Any time you use the Dashboard to change your site, you may can return to this tab and click to refresh button to see how it affects your site.
As you can see, it is ridiculously easy to radically change the look of your site with a new theme. The biggest problem with pre-made themes, however, is that they may have features that you want to change or lack features that you want. You may find a theme that you really like but you also may want a different font, or you may want some pages to have a side-bar but prefer that other pages don't.
In subsequent lessons we will learn to alter the CSS of a theme and also will learn how to create a child theme that offers even more options for altering a theme. Even so, I always encourage my students to think of theme exploration, especially free themes, as something akin to 'speed dating.' Don't get too attached to one theme until you have tried out others. Your goal should be to find a theme that is the best possible match to what you are looking for and that requires the LEAST amount of tinkering,
It is also worth noting that I know at least one professional WordPress developer who is very faithful to just one, especially flexible, commercial, non-free theme named Divi. According to him, Divi can be made to look and function however he wants it.