A blind is a bet that is placed before the cards are shown this is to prevent people from only playing the best hands. Before getting further into that I need you to understand "The Button". The Button is a physical marker which denotes which player is the dealer. In most settings the dealer is supplied by the house and is not a player in the game however the dealer button actively keeps track of the player who would be dealing.
A trypical betting structure may be 1/2 if using chips (I will be referring to chips not money if you wish to play for money you may assign the chip value), this would mean that the person to the dealers left is to place 1 chip up before seeing the cards, the person to his left is to place 2 chips. Betting will go clockwise after cards have been dealt, starting with the player to the left of the big blind, 2 chips (or an ammount equal to the big blind) is the minimum a player may pay to enter into the hand. By forcing players to put money into a pot before seeing any cards keeps the gave active.
All action in poker moves clockwise. The person to the left of the big blind will be big blind next hand, the last big blind will be small blind, the last small blind will be dealer. In the case of heads-up play (one-on-one) the dealer will also be the big blind.