First, navigate to the event that you want to edit, and click on the "Tickets" button in the side menu:
Next, click on the "Roster" button on the left, and then click on "Add New Attendee":
It only takes a few moments to fill out the details, and you also have the option to process credit cards transactions as well:
NOTE: Please include all additional costs and fees that you want to pass to your attendee in the Total Cost field. The person will be charged the exact amount you specified here.