Either we can write code on Gridview Rowcreated event or RowDataBound event.
protected void project_grid_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
//Highlighting Row
e.Row.Attributes.Add("onmouseover", "this.style.backgroundColor='#F0D8D8'");
//Reset Row Color(White Color)
e.Row.Attributes.Add("onmouseout", "this.style.backgroundColor='#FFFFFF'");
}
}