This is called Conditional Formatting
You can enable the RowDataBound Event in the markup
<asp:GridView ID="gridview1" runat="server" OnRowDataBound="RowDataBound">
</asp:GridView>
And put this in your Code-Behind file.
protected void RowDataBound(Object sender, GridViewRowEventArgs e)
{
if(e.Row.RowType == DataControlRowType.DataRow)
{
if(e.Row.RowIndex == 0) // This is row no.1
if(e.Row.Cells[0].Text == "ABC")
e.Row.Cells[0].BackColor = Color.Red;
if(e.Row.RowIndex == 1) // This is row no.2
if(e.Row.Cells[0].Text == "CBA")
e.Row.Cells[0].BackColor = Color.Green;
}
}