WordPress allows you to edit your site via the menus and options, however you can expand upon this by using plugins that allow you to utilize CSS code. CSS is a coding language for formatting that can affect color, patterns, setup, etc. We will not go over how to code here but there are many tutorials online that can help teach you how to code.
Learning how to use HTML/CSS can help you make your site look pretty.
Code Academy and W3Schools are good places to start.