If you don't have Blackjack, you can ask the dealer to hit you by using a scratching motion with your fingers on the table. You may draw as many cards as you like (one at a time), but if you go over 21, you bust and lose.
If you and your friend are playing two-player Blackjack (21) and both of you get a Blackjack, it's called a tie or push. This means that the round ends in a draw and neither of you wins or loses.