More div

Make CSS as :

#upleft { 
   width:100px; 
   height: 300px; 
   background:red; float:left; 
}
 
#upright { 
   width:300px; 
   height:200px; 
   background:blue; 
   float:left
}
#below { 
   height:300px; 
   width:400px; 
   background:green 
}
 
And in HTML
 
<div id="upleft"></div>
<div id="upright"></div>
<div id="below"></div>

float:left is your friend, HTML:<br

<div id="wrapper">
    <div id="first"></div>
    <div id="second"></div>
    <div id="third"></div>
</div>
 
The CSS:
 
div {
    display: block;
}
#wrapper {
    width: 400px;
    height:400px;
}
 
#first {
    float:left;
    width: 33%;
    height: 100%;
    background: red;
}
 
#second {
    float:left;
    width: 67%;
    height: 30%;
    background: green;
}
 
#third {
    float:left;
    width: 67%;
    height: 750%;
    background: blue;
}