Click the tab on the navigation bar labelled "Silver." Look through the collection until you find the item you want. Then, on the right side, enter the amount you want to purchase and click "add to cart."
As you will have noticed, there may be two prices listed. One is used when you use a check or a bank wire to send the payment and the other is for when you use a credit card. The first price is known as a cash discount, and it is now common practice in many businesses to offer this differential.
Once you have finished adding the items you want, click the cart icon on the top right hand side of the website. You can then proceed to register an account and choose the method of payment that you wish to use.