3 columns under the header

In this post is just posting random tips and tricks and this from a master of doyok mas. That I will issue a tip and trick how to make a 3 column under the header which I've tried and can berjalanan well on my blog this very simple and just getting destroyed, heheheh! want to know how a simple but useful, follow these steps - these steps:
Enter the code - the HTML code below on this code]]></b:skin> :

#kolom {

width: 960px;

position: relative;

clear: both;

margin: 0px 0 15px -10px;

color: #000000;

float: left;

padding: 0 0;

background: #cccccc;



border-bottom: 2px solid #e6e6e6; }



#kolomkiri {

width: 290px;

float: left;

margin: 0 5px 0 10px;

padding: 5px 15px 5px 10px;

border-right: 1px solid #e6e6e6;

}



#kolomtengah {

width: 290px;

float: left;

margin: 0 5px 0;

padding: 5px 15px 5px 5px;

border-right: 1px solid #e6e6e6;

}



#kolomkanan {

width: 290px;

float: left;

margin: 0 0 0 5px;

padding: 5px;

}



.kolom li {

background:url('https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJEF49BzZ3zPlGuzFbyASKpTwafhu2N8pnVzhtx7R8ryXS-Dk3XH9LyoDF7HDVEaGSl2RyzvIgHY3HUIWYx1xPUlXDcSI87Jr6suX59UNgOnexeDLA2-1Zefj899vW0UGaCoEPUDStPw4/s1600/arrow_icon.png') no-repeat;

list-style-type: none;

margin: 0 0 5px;

padding-left: 20px; }



.kolom ul {

list-style-type: none;

margin: 0;

padding: 0; }



.column ul li {

background:url('https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJEF49BzZ3zPlGuzFbyASKpTwafhu2N8pnVzhtx7R8ryXS-Dk3XH9LyoDF7HDVEaGSl2RyzvIgHY3HUIWYx1xPUlXDcSI87Jr6suX59UNgOnexeDLA2-1Zefj899vW0UGaCoEPUDStPw4/s1600/arrow_icon.png') no-repeat;

list-style-type: none;

margin: 0 0 5px;

padding: 0 0 0 20px;

border-bottom: 1px dashed #e6e6e6; }



.kolom h2 {

background: #cccccc;

color: #000000;

height: 29px;

text-transform: uppercase;

margin: 0 0 10px;

padding: 6px 0 3px 0px;

font: bold 18px Arial, Tahoma, Verdana;

text-align: center; }


then you find the following code<div id='main-wrapper'>


when it met with the code enter the code - the code below the above code

<div id='kolom'>

<b:section class='kolom' id='kolomkiri' preferred='yes' showaddelement='yes'/>

<b:section class='kolom' id='kolomtengah' preferred='yes' showaddelement='yes'/>

<b:section class='kolom' id='kolomkanan' preferred='yes' showaddelement='yes'/>

</div>