protected void Page_Load(object sender, System.EventArgs e)
                       {
                           FpSpread1.Sheets[0].Cells[0, 0].Value = 3;
                           FpSpread1.Sheets[0].Cells[1, 0].Value = 2;
                           FpSpread1.Sheets[0].Cells[1, 1].Value = 3;
                           FpSpread1.Sheets[0].Cells[0, 2].Value = 1;    
                       }

protected void Button1_Click(object sender, EventArgs e)
        {
            FarPoint.Web.Spread.FormulaConditionalFormattingRule formula = new FarPoint.Web.Spread.FormulaConditionalFormattingRule("A1");
            formula.BackColor = Color.Orange;
            FpSpread1.ActiveSheetView.SetConditionalFormatting(1, 1, formula);
        }

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            FpSpread1.Sheets(0).Cells(0, 0).Value = 3
            FpSpread1.Sheets(0).Cells(1, 0).Value = 2
            FpSpread1.Sheets(0).Cells(1, 1).Value = 3
            FpSpread1.Sheets(0).Cells(0, 2).Value = 1
        End Sub

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
            Dim formula As New FarPoint.Web.Spread.FormulaConditionalFormattingRule("A1")
            formula.BackColor = Drawing.Color.Orange
            FpSpread1.ActiveSheetView.SetConditionalFormatting(1, 1, formula)
        End Sub