First of all you will need to create a div for the blue background. Then you will need to create a div inside of the blue background div to hold your content.
<div id="blueBackground">
<div id="contentDiv">
<!-- your content here -->
</div>
</div>
Next you will style the div's with CSS
#blueBackground {
background:#hexcolor;
width:100%;
padding: 40px 15px; /* first number sets vertical padding - second sets horizontal */
}
#contentDiv {
width: 100%;
}