"Poker players can call the big blind to stay in the hand or raise after looking at their hole cards. Action begins with the player under the gun (immediate left of the big blind). If the big blind is $4 in limit hold’em a player can call the $4, raise to $8, or fold their cards. This action continues clockwise around the table until all players have made their decision to fold, call, or raise the betting action for that round."
"Poker players can call the big blind to stay in the hand or raise after looking at their hole cards. Action begins with the player under the gun (immediate left of the big blind). If the big blind is $4 in limit hold’em a player can call the $4, raise to $8, or fold their cards. This action continues clockwise around the table until all players have made their decision to fold, call, or raise the betting action for that round."
http://www.ultimatepoker.com/how-to-play-online-poker/poker-tips/