After receiving the initial two cards, you have these options: You can "Hit", "Stand". take Insurance, or Double Down.
Hit: Take another card (as long as you don't exceed 21)
Stand: Take no more cards.
Insurance: When the dealers face-up card is Ace, you can take an optional insurance - insurance is always half your bet.
Double: If the first 2 cards count equals either 10 or 11, then you can double your bet and receive only one additional card.