By registering with the website you create an account and this makes it quick and easy to checkout as your details are saved, and you can also view your order history.
You can register on the checkout page only at the moment, there is a checkbox half way down the checkout form – click this and it will ask you to set a password.
Once done and you complete your transaction you now have an account and can use these login details each time you buy from us.
You can not currently create an account after your order, and if you checkout as a guest and then order with an account your orders are not linked so you do not see guest purchases in your account.