What is the structure of a social network in languages?

Question

Social media

I want to write my social network, please tell me if I study this:
Is this knowledge enough or is my idea wrong?
I would like to give preference to the java language, as I understand it, the engine of my social network (and this is a website) will be in java, other languages ​​​​will be responsible for the markup, how it will look, where it will be located (server part) and so on, right ? Correct me if I'm wrong please.
1. HTML/CSS
2. Bootstrap
3. PHP/MySQL
4. GIT
5. Codeigniter
6. Javascript/jQuery
+
Java

Answer 1

I would like to give preference to the java language, as I understand it, the engine of my social network (and this is a website) will be in java, other languages ​​​​will be responsible for the markup, how it will look, where it will be located (server part) and so on, right?

If you want, give. You can write on anything.

Is this knowledge enough or is my understanding wrong?

wrong, not enough. after studying all this, you still have 5 years of studying other things (all day long) to build at least something that works normally. And 15 years to be able to "unwind" it at least a little.
If you want to "create a frame" and then assemble a team of people who know how to do all this, so that they "finalize" it - then I'll be honest, they will throw out everything that you have built there.
And they will ask you "what for do we do all this for you?". Your answer must be very persuasive.
And if they take it and start developing it further, then put an end to them - they will not have the skill to create such a system.