The blinds are forced bets amount that begin the game. There are two blinds, the small and the big. The Small Blind is placed by the player directly to the left of the dealer (dealer button), with the Big Blind to the left of the Small Blind. The bets amount of the blinds of Small Blind is usually half the Big Blind.
Even if someone goes all-in, if there are more than one player with plenty of chips left, the betting action can continue. However, if the player who goes all-in wins, the chips that can be obtained are up to the amount that he/she bet, so the chips that are bet more than that are managed by creating a pot called a side pot, which is different the main pot.