Highlight GridView Row during Bulk Edit with CheckBox in ASP.Net

Hi All, I am following this article in aspsnippets. I followed each and every line, but when the user check the check box, the row become highlighted and it turns light yellow. I could not figure out where the code to make the row yellow/highlighted is and the gridview in my code is not turning yellow either. Below is the link http://www.aspsnippets.com/Articles/Bulk-Edit-Update-Multiple-Rows-in-ASPNet-GridView-using-CheckBoxes.aspx any help will be greatly appreciated.