Check out this MoodleDocs article for information on Moodle's wiki activities. 

Working with Wikis and Groups:

Group mode can be one of three levels:

• No groups - there are no sub groups, everyone is part of one big community
• Separate groups - each group can only see their own group, others are invisible
• Visible groups - each group works in their own group, but can also see other groups

Creating the Wiki 

1. Toggle Edit mode on.
2. In the week you want to add the Wiki Activity too, select Add Activity or Resource and then scroll through the Activities till you find Wiki Activity and then click on Add
3. Name your Wiki, add a description if you want
4. Choose how you want the wiki activity to work in the Wiki Mode, it can be collaborative or individual work from students
5. Name the first page of the wiki
   NOTE: This name cannot be altered once you’ve saved the settings. Name carefully
6. Scroll down and select Save and Display
7. You’ll be taken to a new page, and you can choose what type format the wiki is set up as. It’s okay if you leave it as HTML 
8. After this, you will once again be re-direct to the first page of your wiki. Add content and then save.