Once logged in to Workflow, click "Inbox" on the left-hand side of the page (Fig 1 - #1). You should now see all cases that are currently assigned to you. Double click the case you would like to review (Fig 1 - #2).
Once you have opened the case you would like to review, please review the case and scroll to the bottom for your available options (Fig 2). Select "Submit" when you are done reviewing (Fig 2 - #1)
Note: Options available to you will depend on the workflow and case in question. These options can include Approve, Deny, Cancel, Add Comments, Upload Files, etc.