From your Covidence homepage, you can open a new review by clicking "Start a new review".

Your Covidence homepage will be the first page you see after logging in. You can also reach this page by clicking the Covidence logo at the top left. 

Your review will need a unique title. This can be changed later in Settings.

Once you've given a unique title to your review, select which account you'd like to use to open the review. If you select an institutional account subscription, the review and its progress will be visible to the institutional admins.

Finally, click "Create Review". You'll be prompted to invite any review collaborators, and then you're ready to go!

For information about opening a Cochrane review, please see this article.