After selecting "Register Now", fill out the Registration form that pops up, select a ticket quantity.  You can pay the deposit for more than one person but will need to fill out a separate registration form for each attendee.  This will take you to checkout where you can pay using PayPal or your credit card.   If you don't have a PayPal account there is an option below the login box that allows you to select "Pay with a Debit or Credit card".