When you order an item, then it is added to the Shopping Cart. This can be found as soon as there are items in it, on all pages at the top right. You can then continue shopping or, as it states, "Go to Checkout" to complete your order.

You can pay for your purchase using PayPal and will receive all articles which need not be sent by mail immediately after payment. European customers can also pay by bank transfer to a German bank account. Shipping and downloading will then be deferred until receipt of payment.