How to make an analogue of an open source website?

Question

Web development

Let's say there is a certain foreign site with open source code on GitLab.
I need to make its analogue, the Russian version of the site, maybe remove something somewhere, add it, but make it look like a site.
At the entrance, basic knowledge in web development, more precisely in its current study, I mastered basic HTML, CSS, I continue to study Javascript, at the exit I need a site in terms of functionality, I think something in between, maybe a little lower, definitely not Facebook or VK.
What to continue to study, where to dig, how to translate the site into Russian, is it possible to do it yourself without a command if the source code of the site is already there? Alas... I don't want to write the name of the site yet...

Ps The site continues to develop, which I don't have time to study :(

Answer 1

What to continue to study, where to dig, how to translate the site into Russian, is it possible to do it yourself without a command if the source code of the site is already there? Alas ... while I don’t want to write the name of the site ...

How to answer a question when you didn't provide initial data :)
What is "your site"? SPA, static, website written with some framework? Based on the data, there will be different solutions, since there are always ready-made modules that solve specific problems.

Alas ... while I don’t want to write the name of the site ...

Everyone will not care, stealing the "idea" or code is the last thing they will do here. So if you want a roadmap for solving a problem, you have to "fork out"