You'll be upgrading existing English text and translations so that they are translatable with MediaWiki's Translate extension, which greatly improves translation workflow hence making coverage of translated docs vastly broader. You must not translate yourself, that's forbidden by the rules. Detailed steps:

1. Read the basic help, translation tutorial, page translation example and reference manual, language policy.
2. Pick as many pages to migrate to Translate as needed to reach the task goal (see below). Polish the English text as fit/possible to avoid migrating very obsolete/low quality text, skip pages where unsure. Follow the steps for migration and strike a page on the list when it's prepared for translation; ask questions on the list's talkpage.
3. A translation administrator will now approve the page for translation at their discretion. When it's approved, complete the job: copy the old translations to corresponding units with Special:Translate. You don't need to know the language you're migrating, only to identify which paragraph corresponds to which, even though it's not a loyal translation (machine translation can help grasp the meaning if the layout of the page doesn't provide enough hints).
4. When you're done, add in this melange task a link to the stats for each page (example). To have this task marked done, you need at least one page marked for translation; and a total of at least 120 translation units (i.e. paragraphs/strings) counting those created in the source language (English) and those migrated from existing translations (visible in the stats, row "All languages together", as difference between the columns "Messages" and "Untranslated"). Alternatively, 30 Manual:$wg* pages (last section of the list; those are not in priority).

Important: All the communication with mentor(s) about the task will happen on the list page and its talk page, not in Google Melange! Contact the main mentor, Federico Leva (Nemo) via wiki talkpage or on IRC directly if you get stuck in any of the steps.

Students are required to read Wikimedia's general instructions first.