I use to think I was moderately good at computers

That doesn’t say a lot. It all depends what you already can do with a computer. Setting up a server is already somewhat technical stuff. Using a computer to browse the web and click stuff, is not—heck, even I use Linux and I’m no expert ;)

Just looking fro advice on my first build.

As a true beginner, imho you need a beginner-friendly distro aka one that will do most of the work for you. I use Mint and I like it a lot but there are plenty choices available (and I don’t run my own server neither). So, take some time to find one you would like to use. Also, if you only want to create a server (not use it as your personal computer) you should focus on a distribution for servers, not your usual end-user one. I mean, any distribution can be used to setup a server (they all have access to the same tools) but some are more focused on general users (like Mint) while other are more on technical users like people that will admin a server.

So, my first advice would be to tell you to decide what exactly it is you want to do with that Linux computer. From that you will then be able to pick a good distro and then start reading teh docs as needed. And that reading will also depends your skills level. Something like Arch (a great distro) has an amazing Wiki, like it’s really excellent. But it’s also very technical and not that beginner-friendly. Then, there are things like https://linuxjourney.com/ that are so cool for beginning but won’t be as complete ;)

I would not try to setup a server if I had not started using Linux already to get some familiarity with the system and its basics. For that you can pick any distro you like. Once again, I would suggest Mint out of personal preferences but I should probably say that before that I was a very happy Arch user too (I just realized I preferred to get less frequent updates)… There is not one best distro everyone would agree upon but there are various ones that are better suited to whatever type of user one may be.