Updated for 7.0
On the left-hand side of the screen in the navigation bar, select Merchandise. This will take you here:
Scroll to find the item you want to order.
If the item is out of stock, there will be a red Out Of Stock message at the bottom of the item window.
Once you have found the item you want to order, type in the amount you want to order in the window next to Qty. It will look like this:
After entering the amount you want to order, click the green Add to Cart button to the bottom right of the item.
A pop-up window displaying your cart will appear to the left of the screen that looks like this:
When you are ready to check out, click the green Checkout button at the bottom of the pop-up window to the left. This will take you here:
Scroll to the bottom of the Checkout and enter your billing address and credit card details.
Once you have entered your billing address and credit card, click the green Submit Order button at the very bottom of the page.