For this task, you should have already used Gerrit and Git a little bit before.
You'll also have to write a wiki page: You need some English and writing skills (correct punctuation etc.). :)

gerrit.git.wmflabs.org is a Gerrit test instance. It runs the same code as our main ("production") Gerrit instance, (where the 'real' code review happens).

It can be used for testing bots or wrappers around Gerrit's Rest API for development purposes. But there is no information about this test instance and how to use it.

There should be a dedicated short tutorial that explains:

• What is gerrit.git.wmflabs.org?
• When and who should use it?
• How to create an account on it? Tip: First register
• How to clone repositories and push changes? Tip: For changes to show up in Gerrit for review, use git push origin HEAD:refs/for/<branch-name>

Start by creating a draft on a subpage of your user page (for example if your user name is ABC123, start on https://wikitech.wikimedia.org/wiki/User:ABC123/Gerrit_test_instance) and provide a link here, before creating the actual page.
On https://wikitech.wikimedia.org , use the same username and password as for gerrit.wikimedia.org. Do not use the same password for http://gerrit.git.wmflabs.org !

Once your draft looks good, create the actual wiki page on wikitech.wikimedia.org. After that, link your tutorial from a few places:

• "See also" section on https://www.mediawiki.org/wiki/Gerrit
• "Quick links" section on https://wikitech.wikimedia.org/wiki/Gerrit
• Gerrit section on https://www.mediawiki.org/wiki/Continuous_integration/Dev
• <add a venue>

See Help:Editing or the VisualEditor help.
Note that wikitech.wikimedia.org has a separate log-in from www.mediawiki.org.