Once you see what skills are required for building a website, you can decide whether you want to invest the time in learning them. I highly recommend that you do learn these skills, as it will provide you with so many more options when building and maintaining your websites. Also, if you want a career developing websites, these skills are essential.
A domain name is the bit of the URL (the long address in your browser’s search bar) that identifies a web page — in this case your website. You can register them separately at sites like GoDaddy and Namecheap, but website builders offer to do it for you when you sign up with them. Most provide it for free (at least initially), while a handful charge a few extra bucks.
WordPress vs. Joomla/Drupal: Drupal is a very powerful platform that is popular with web developers and experienced coders, but it comes with a very steep learning curve that makes it a bad choice for beginners. Joomla is similar to WordPress and works great for online stores, but you’ll need at least a little bit of technical coding to make it work the way you want.