I've installed Arch a dozen times at least over the years on various machines.

First off, some advice. People will tell you to watch videos or read some specific guide, and by all means do so to get an overview of the process, but I'd highly recommend double-checking everything against the official install guide. It's fairly terse but contains everything you need to do, and if you research the topics you don't understand you'll learn a lot quickly. This is best done in a virtual machine the first time unless you have a spare machine laying around.

Overall, it amounts to creating the install medium, booting it, any post boot configuration (including networking), partitioning and mounting your disk(s), writing some config files and installing the base packages and a bootloader, plus anything else you may need or want. I'm glossing over a lot of individual steps and "anything you may need or want" is essentially endless, but you get the point.

Overall it's involved but not terribly difficult. Like I think others have said, fairly similar to building a desktop from parts. Gentoo is a step up, and installing Linux From Scratch another few steps above that.