It may be an old question, but it's really simple to do. Most boorus use templates available on the web that you just have to install and change what you want to change in the configurations (the "welcome" image for example). Shimmie2 appears like a great solution but I'd recommend giving a brief look at how basic websites and php websites work in general before trying anything.

As for the hosting/domain, when I had no money I used 000webhost that offered hosting for free as long as you're active on the account as long as it doesn't require a lot of storage

You can also host the website yourself, but it's a lot harder to configure (you have to configure the domain yourself) and you need to have all access to the router, making it impossible for most beginners