Now that you have found the item you're looking for, you have a couple of options.
1) You can add to the basket and rapidly keep shopping without having to navigate to and from the cart.
2) You can click on the item and see more information under the description, see if the item can be customized and if there are any applicable mix and match or standalone discounts.
The first method is the quickest but you may be leaving some money on the table by not buying in quantity. Once you become more familiar with the store and the discounts, option one will be the way to go to streamline your ordering as the discounts will still be reflected in the cart if the specific quantity is reached.
The next articles will cover the discounts and customization options if applicable and provide information on back in stock dates for out of stock items.