How to roll back Wiki changes
You can roll back and undo page changes by clicking the "History" button from your tab list:
From here you will see a history of the most recent revisions to your pages. You can rollback or undo recent changes by clicking the small gear icon below:
Comparing Revision History
You can compare the various different Wiki revisions from the same "History" tab. You will just need to select two revisions from your list and click "Compare Selected Revisions".