asp.net background is not appearing in the browser

I just start making web site in asp.net using microsoft visual studio 2008. I have called a css file and make a 开发者_运维知识库background image in one of my div in header. The problem is that that background image loads in the design part of the microsoft visual studio but does not loads in the web browser. I am not getting type of design what i want. Should i have to add anything extra with ?

{background-image:url('header_‌​bg_2.jpg'); background-repeat:repeat-x;}

Try this.