How to set the center of a Div control

Margin is to set the margin, it has four values, margin:4px 5px 5px 5px, respectively, the top margin, the right margin, the bottom margin, and the left margin is set clockwise from the top, if the individual settings, he has margin-top:3px margin-right:3px;margin-bottom:3px;margin-left:3px; If the margin is followed by two values, he says, the margin is the same, the left and right margins are the same, margin:0 auto;  This 0 is the upper and lower margins are 0,auto is automatically resized, here is the right and left margin is the same, is centered

margin:0 Auto

How to set the center of a Div control