What the others said is very much true, but since info like that isn't easily found if you're just starting and don't know where to look, I'd recommend starting with the easy stuff and working yourself up to the more complex stuff. Be aware that it'll probably take a long time until you'll be able to actually create a whole, functional adoptables website (at least if you want functionality similar to the sites you listed).
Start with HTML and CSS. Those aren't programming languages but there for structuring your website. It's good to have a pretty firm grip on them. HTML5 is the current standard, but that should come up once you do some research and find tutorials.
Javascript is what I would recommend tackling next. It's what gives your website an interactive component and makes it more dynamic. Since it might not be that easy to find - I can recommend this (completely free) javascript course:
https://watchandcode.com/p/practical-javascriptIt teaches you the most important concepts and features in a practical and easy to understand way (imho, at least). I did that course and think it's good.
And as for your server-side programming language... pick the one you prefer. PHP is very wide-spread still, yes, but it's really not as important to pick the most popular language for your purposes. The major languages out there all have their uses. That said, it's still probably easier if you pick PHP, because there are adoptables "frameworks" out there like kitto.
So, just pick one, find tutorials or courses for it, and go.
And lastly... databases! There is a lot to learn about databases and how to effectively (and safely) use them. Don't underestimate this one.
I recommend learning by doing. Do try to hand-code while you learn, until you get a grip on it. The more you try out, fail and try again until it works, the better you'll get at it (and faster, just reading won't help you).
I guess that's a lot to take in (and it might sound way too much), but it's actually quite fun if you're that way inclined
Having patience definitely helps.
(to make it more fun - you can absolutely start making more basic websites (and add functionality / edit to improve the more you learn) while you learn! I just wouldn't recommend putting them out there on the web. Leave them in your local environment / on your computer. Imho it's more fun if you create things you actually want to create ^^)
