Wikipedia can be used to compliment the work of libraries in several ways.
The Basics of Editing Wikipedia
While there are a variety of online instructions on Editing Wikipedia, the following are lesson plans or guided tutorials for first time users.
#1Lib1Ref Lesson Plan (10-20 minutes)
Bi-annual hack-a-thon's editing lesson to partipicants
The Wikipedia Adventure (60 minutes)
Interactive online tutorial in 7 sections
Wiki Education Student Training Modules (90 minutes)
"Basic" section includes 5 guided online tutorial
Art + Feminism's Learn to Edit Resources
Visually appealing instructions and videos.
Existing Wikipedia Edit-a-thon (Hackathon) events
#1Lib1Ref
Biannual event encouraging reference librarians to conduct training lessons and edit-a-thons on Wikipedia. Great (although limited) lesson plan.
Art+Feminism Wikipedia-edit-a-thon
Includes a great “quick guide” for organizers Also has a great visual “How to Edit” page