How to include libraries using composer?

Question

PHP

I still don't understand how composer works at all. I need to use a CSS parser in a Sabberworm project , but I don't know how to install it.
The Readme file does not help because I just don't understand how composer.
I would appreciate a specific code action plan , as well as links to articles about composer for beginner programmers :)
Thank you!

Answer 1

you must have a composer.json file in your project, you need to add the line
"sabberworm/php-css-parser": "*"
to it and run composer update
If you do not use composer in your project, you can install it manually by downloading from github

Answer 2

create a project
, connect dependencies.
It will prescribe and install this business, and in the file in which you want to use these dependencies (or at the entry point), write:
all.