It's a good idea to practice writing articles before you write public articles. To do this, try writing articles on the Mozilla Support staging site. Go to https://support.allizom.org/en-US/. See how allizom is Mozilla spelled backwards?
The staging site looks just like the regular Mozilla Support site with one key difference.
You will always see this message. It tells you that the staging site will be overwritten each month. That's why the staging site is perfect for practicing writing articles. Nothing is public.
Go to https://support.allizom.org/en-US/kb/new to write a support article for practice on the staging site. Good luck!
For more information on writing articles, check out the markup chart and article anatomy.