As an AI language model, I am not capable of playing games or accessing the internet. However, I can provide you with some information on how to play Xì Dách (Blackjack) online.

To play Xì Dách online, you need to find a reputable online casino or gaming website that offers the game. Once you have found a suitable platform, you can register an account and make a deposit to start playing.

The objective of Xì Dách is to have a hand value of 21 or as close to 21 as possible without going over. The game is played with a standard deck of 52 cards, and each card has a point value. Number cards are worth their face value, face cards (Jack, Queen, King) are worth 10 points, and Aces can be worth either 1 or 11 points, depending on the player's choice.

To start the game, the dealer deals two cards to each player and two cards to themselves, with one card face up and one card face down. Players can then choose to "hit" (receive another card) or "stand" (keep their current hand). The dealer will continue to deal cards until they reach a hand value of 17 or higher.

If a player's hand value exceeds 21, they "bust" and lose the game. If the dealer's hand value exceeds 21, they also bust, and the player wins. If neither the player nor the dealer busts, the hand with the highest value wins.

There are also additional betting options in Xì Dách, such as splitting pairs, doubling down, and taking insurance against the dealer's potential blackjack.

Overall, Xì Dách is a popular and exciting game that can be enjoyed online with friends or against other players from around the world.