As a general rule, the moderator will not process a lynch on a player until the majority of the living players are voting for that player.
When roles such as Doublevoter enter the game, the moderator may or may not take the extra vote into consideration when deciding the quota needed to lynch a player. If not, the quota needed to lynch a player is decided based on the number of players alive instead of the number of votes in the game.
A vote typically is cast either by bolding the word "Vote" followed by the player's name(ex. Vote: PlayerName) or by using the [vote] tag(ex. [vote]PlayerName[/vote]).
See also Unvote.