Step #1: Create a Discord account
Step #2: Login to the site
Step #3: Add new words (you can add them either by selecting a language, and then pressing a “Translate missing words for this language” button, or to simply select “Browse words” and fill in the missing entries).
Step #4: If you spot a mistake in existing translations, press the “Correct this word” button and add a comment
I believe the website is fairly simple to use.