How to contribute with Plug-In translations?

I just installed the Waste Collection Plug-In. I am missing the German translation. So I would like to create the de.json file and give it to the community. I looked into the repo for the plugins and found the translation files. Please can someone explain to a noob like me how I can test my own json file and how to bring it to the community? Or would it be easier/faster if I send the file to someone?