I want to create 3 divs inside outer div.The outer div is 72%.The three inner span with classes first,second,third should be 24%.
Scrap the span, assign a class to all 3 divs instead, then use float: on the class. If this doesn't work, you might have an easier time with display: table-.
span
float:
display: table-
http://www.w3schools.com/cssref/pr_class_display.asp