centreblock margin code

I am trying to get my centerblock to move up so it is flush with the sidebars. I tried to change the code but realised it is dependent on the code for the heading with the date (H2). I can’t figure out where in the H2 margin code I should change. I don’t understand what each number in the margin code stands for..here are the 2 sets of css codes..

h2 {
margin: 12px 210px 20px 190px;

padding: 2px 10px 2px 10px;
font-size: 16px;
color: #eeeeee;
position: relative; /* Position is declared “relative” to gain control of stacking order (z-index). */
width: auto;
min-width: 120px;
background: #5f7797;
z-index: 3; /* This allows the content to overlap the right menu in narrow windows in good browsers. */
border: 2px solid #354463;
}

.centreblock, .navigation {
position: relative; /* Position is declared “relative” to gain control of stacking order (z-index). */

width: auto;
min-width: 120px;
margin: 0px 210px 20px 190px;
border: 1px solid #5f7797;
color: #333333;
background: #bfc4cb;
padding: 10px;
z-index: 3; /* This allows the content to overlap the right menu in narrow windows in good browsers. */
}