I have the front end ready, what about the backend?

Hi, I am currently developing my first website project. Although I have some experience with C and Python, I had to learn in the last week html, css and JS, which i definitely liked. That being said, i was able to produce a static website capable of displaying what i want, which is currently only on my computer, and I can see it by dragging it to the web browser.
Here is the problematic part for me. Although front end development has many many tutorials and guides and overall assistance, I don’t find that to be true for the backend.

Let me explain what I intend to do, so you can advise me properly.
I am producing a website for my parents restaurant. It should be simple as hell. Just displaying the menus, some photos and stuff, and that’s about it. However, it should also be capable of letting the user choose and order something. Which means i want to have something like a shoppingCart connecting to a database, or a textfile with the order, that is sent to the server, and managed by it. (a note here: the user will NOT pay for the order online, but do it personally in the restaurant. also i want to require login with facebook so i can use a script to verify it’s a real person, so validating the order)
My objective is then to use some script to send those orders to my parents email, so they can view then, and produce them for the clients.

That being said, my actual question is, what do you suggest me to do to implement this part? I spent the last two days googling and learning stuff like php, sql, django and so on, but i feel like i did not produce valuable knowledge. Can anyone point me in the right direction, as to how implement a simple solution for the problem?
Thank you very much.

Sending out emails is easy, but if you’re going to force your users into the Facebook ecosystem, why not have the ordering system managed by a chat bot? I’m sure there’s some way to make the bot notify your parents when an order has been received.

I would suggest you go through the backend lessons here. Learn node js and get some experience setting up basic servers. Emails could quickly become a problem and there are a number of libraries for nodejs that will let you log in with many different social media sites. It should only take you about a week to get through the basics, and have something simple up and running.