How To Add "Two Columns" below blogger Header ?

1.Log in to your dashboard--> layout---> Edit HTML

2.Scroll down to where you see like this code.
<div id='header-wrapper'><br /> <b:section class='header' id='header' maxwidgets='1' showaddelement='no'><br /><b:widget id='Header1' locked='true' title='YOUR BLOG TITLE (Header)' type='Header'/><br /></b:section><br /> </div>

3.Now add below code between </b:section> and </div>
<b:section class='sidebar' id='magazine-left3' showaddelement='yes'><br /><b:widget id='Text513' locked='false' title='Column 1' type='Text'/><br /></b:section><br /><br /><b:section class='sidebar' id='magazine-right3' showaddelement='yes'><br /><b:widget id='Text523' locked='false' title='Column 2' type='Text'/><br /></b:section><br /><br /><div style="clear: both;"></div>

4.Now Find below code.
]]></b:skin>

5.Add below code before ]]></b:skin> tag.
#magazine-left3 {<br />width: 30%;<br />float: left;<br />}<br />#magazine-right3 {<br />width: 65%;<br />float: right;<br />}

Note: You can change values of width,as your choice.

6.Now save your template and you are done.