You will go into Employee > Leave Approval Tab Within the portal. There it will list all your outstanding request per employee. When an employee submits a leave request you will receive an email notifying you.

You can approve, reject, or view comments. Also, you can click into request to see some additional details regarding their balances.

If you click on "Comments" a window will pop up that displays comments attached to the request by the employee who submitted it. Also, you can add additional comments that the employee will be able to see 
                   as well.

Once Approved the status will be updated to reflect the change and give you the ability to unapprove if there was a mistake.

Email Notifications:

As noted above, when an employee you supervise submits a leave request you will receive an email notification. When  you approve or deny the request, the requester will receive an email notification as well of the updated status.