To open a box left click the box you want to open. There are 3 ways to flip the cards in any pack, Hold left click and drag your mouse over the set cards, left click the cards, or click the "Open Pack" button. Whenever your box is empty feel free to click Reset box to open the next box.
To view your collection/set list, right click the box instead. This will pull up the set list, to see how many of any card you own, hover your mouse over the card.