Click 'Buy item' then click the basket icon. Click 'checkout', fill in your details, and then there are currently three methods of payment:
Pay by PayPal, clicking the PayPal button.
Pay by credit/debit card; for this you will have to telephone, and your details can be given over the phone.
Send a cheque to the address given (it is wise to send a message to say the cheque is on its way, to secure your order).