Leo recommends a template based web builder like Squarespace, Weebly, Wix or Wordpress. Squarespace is great because it's free to start out, and then Arthur could either choose a template and customize it, or ask a group of experts help him add functions like logins, databases, social media extensions, etc. It's very expensive to do a professional grade website. He'll be much better off with something that's simpler and can be customized.
(Disclaimer: Squarespace and Wordpress are sponsors)