Public Sub Add( _
   ByVal item As IConditionalFormattingRule _
) 

Dim instance As ConditionalFormatting
Dim item As IConditionalFormattingRule
 
instance.Add(item)

public void Add( 
   IConditionalFormattingRule item
)

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 = 10;
                           FpSpread1.Sheets[0].Cells[0, 2].Value = 1;              
                       }

protected void Button1_Click(object sender, EventArgs e)
        {
            FarPoint.Web.Spread.UnaryComparisonConditionalFormattingRule unary = new FarPoint.Web.Spread.UnaryComparisonConditionalFormattingRule(FarPoint.Web.Spread.UnaryComparisonOperator.EqualTo,10);
            unary.Operator = FarPoint.Web.Spread.UnaryComparisonOperator.EqualTo;
            unary.Value = 10;
            unary.BackColor = Color.Red;
            unary.FontStyle = new FarPoint.Web.Spread.SpreadFontStyle(FarPoint.Web.Spread.UnderlineFontStyle.None);
            unary.FontStyle.RegularBoldItalic = FarPoint.Web.Spread.RegularBoldItalicFontStyle.Bold;

            FarPoint.Web.Spread.TopRankedValuesConditionalFormattingRule topRank = new FarPoint.Web.Spread.TopRankedValuesConditionalFormattingRule();
            topRank.IsDescending = true;
            topRank.BackColor = Color.Tomato;
            topRank.ForeColor = Color.Yellow;

            //CondtionalFormatting Construtor
            FarPoint.Web.Spread.ConditionalFormatting cf = new FarPoint.Web.Spread.ConditionalFormatting(new FarPoint.Web.Spread.Model.CellRange(0, 0, 2, 2));
            FarPoint.Web.Spread.ConditionalFormatting cf1 = new FarPoint.Web.Spread.ConditionalFormatting(new FarPoint.Web.Spread.Model.CellRange(0, 0, 2, 2), topRank, unary);
            FpSpread1.ActiveSheetView.ConditionalFormatting.Add(cf);
            FpSpread1.ActiveSheetView.ConditionalFormatting.Add(cf1);
            //OR
            //SetConditionalFormatting Overload
            //FpSpread1.ActiveSheetView.SetConditionalFormatting(cf, cf1);
        }

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 = 10
            FpSpread1.Sheets(0).Cells(0, 2).Value = 1
        End Sub

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
            Dim unary As New FarPoint.Web.Spread.UnaryComparisonConditionalFormattingRule(FarPoint.Web.Spread.UnaryComparisonOperator.EqualTo, 10)
            unary.Operator = FarPoint.Web.Spread.UnaryComparisonOperator.EqualTo
            unary.Value = 10
            unary.BackColor = Drawing.Color.Red
            unary.FontStyle = New FarPoint.Web.Spread.SpreadFontStyle(FarPoint.Web.Spread.UnderlineFontStyle.None)
            unary.FontStyle.RegularBoldItalic = FarPoint.Web.Spread.RegularBoldItalicFontStyle.Bold

            Dim topRank As New FarPoint.Web.Spread.TopRankedValuesConditionalFormattingRule()
            topRank.IsDescending = True
            topRank.BackColor = Drawing.Color.Tomato
            topRank.ForeColor = Drawing.Color.Yellow

            'CondtionalFormatting Construtor
            Dim cf As New FarPoint.Web.Spread.ConditionalFormatting(New FarPoint.Web.Spread.Model.CellRange(0, 0, 2, 2))
            Dim cf1 As New FarPoint.Web.Spread.ConditionalFormatting(New FarPoint.Web.Spread.Model.CellRange(0, 0, 2, 2), topRank, unary)
            FpSpread1.ActiveSheetView.ConditionalFormatting.Add(cf)
            FpSpread1.ActiveSheetView.ConditionalFormatting.Add(cf1)
            'OR
            'SetConditionalFormatting Overload
            'FpSpread1.ActiveSheetView.SetConditionalFormatting(cf, cf1)
        End Sub