How do I use this?

The first view you see is the Basic Strategy utility. Using the left slider, you can pick what you currently have in your hand. If you have Aces or pairs, scroll down to find your matching hand, otherwise just select the number that matches the total of your hand. Using the right slider, select what the dealer is currently showing.

Once you select both cards, the app will simply report what you should do. Hit and stand are the most obvious. Split means to split your hand and play two hands, reading up on basic Blackjack rules will explain this. Double means you are doubling the bet, but you can only hit one more time, then you are forced to stand. Sometimes it will say "Double (or Hit)" or "Double (or Stand)". This means if it is not possible to double up, those are your next best options.

The "Decks" button in the upper right lets you select the number of decks in play. This affects the calculation among different hand combinations.

The second view is a Card Counting utility. Card counting is a way of determining if the deck is progressing to your advantage or the dealer's advantage. As cards are dealt out, simply touch the card dealt, and the count will update in real time. As it goes positive (green), this means the deck is in your advantage. As it goes negative (red), this means the deck is to the dealer's advantage.

The "Strategy" button in the upper right lets you select which strategy you want to use. Different strategies change the count differently based on which cards are played, and sometimes increase or decrease the count more dramatically. Not all cards affect the count.

Let me know if you have any questions.