How do I connect the things I downloaded from Composer with my project?

Question

I downloaded the stuff from Composer(ñ sei se ta td certo). I downloaded the exe Composer from the official website there and the git bash. So I wanted to use a github project that is OPEN BOLETO. Then I put that require "Kriansa/openboleto": "v1.0" in the JSON Composer that is in C: Users Administrator. My project is in C: wamp64 www.

So I typed Poser update then everything went well there, but how I put together with my project so I can use?

And another question, there is no more manual way to do this, like just by stirring some files and using PHP include or require?