How are the cards shuffled?

So we create a random number thats 226 bits long. long enough to represent every possible combination of a deck of 52 cards. If you want to know how many unique decks that is, watch this video...

You will never play the same game twice.

This amazingly unique deck number is converted into a deck of cards. For example it might be:
[5d 0d Jd Qd 5c 6c 7c 3h 4h 7h Kh Ah 3s 5s 7s 8s As 3d 4d 6d 8d Kd 3c 8c 9c Kc 5h 9h Jh Qh 2s 9s Js Qs 3d 4d 6d 8d Kd 3c 8c 9c Kc 5h 9h Jh Qh 2s 9s Js Qs]

If the deck cut option is used, whatever spot in the deck the player picks becomes the top of the deck. So if they end up picking the Kd (which of course they can't see the face just the location in the deck) the deck would be:

[ Kd 3c 8c 9c Kc 5h 9h Jh Qh 2s 9s Js Qs | 5d 0d Jd Qd 5c 6c 7c 3h 4h 7h Kh Ah 3s 5s 7s 8s As 3d 4d 6d 8d Kd 3c 8c 9c Kc 5h 9h Jh Qh 2s 9s Js Qs 3d 4d 6d 8d]

for a game like Spades, we would then we deal out each card to each seat sequentially until each player has 13 cards and the game starts.
So one seat would be [Kd Kc Qh Qs Qd 3h Ah 8s 6d 8c 9h 9s 4d] sorted it in your hand it would read [4d 6d Qd Kd 8c Kc 3h 9h Qh Ah 8s 9s Qs]

thats pretty much it.