Learn how to use Gerrit for code review, by submitting a patch
Many Wikimedia tasks want you to submit your work to Gerrit. We have a test instance of Gerrit, live on https://gerrit.git.wmflabs.org/. In this task, you should upload a patch to this test Gerrit instance.
Please read through Gerrit tutorial (please bear in your mind that in this task, you should work on test instance living under gerrit.git.wmflabs.org and NOT on the main instance gerrit.wikimedia.org; everytime this tutorial talks about gerrit.wikimedia.org, imagine it's talking about gerrit.git.wmflabs.org). With the help of this tutorial, upload a patch to this repository. This commit should add new file "yourusername.txt" (please use the same nickname as on the GCI site), which can contain any text you want.
You also want to read https://www.mediawiki.org/wiki/Gerrit/Commit_message_guidelines, which guides you how to write good commit messages.
If the task is not claimed yet, you can write instructions how to use the test instance in this task.