Simply search for the product you are looking for by searching for a word in the search menu, or by selecting the category relating to your item. Once you see the product you would like to purchase, click "Add to cart".
Once all of your products have been selected, click on the checkout icon in the top right corner of the screen, review your order, then click "Continue to Checkout".
A notification will pop up asking to you confirm, then you're ready to proceed. If you already have a login, it will ask you to log in, if not it will ask you to continue as a guest. Once you have entered your billing and delivery details, your payment is ready to be processed.