------------------------
Webフォームクラス
------------------------
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
　　If IsPostBack Then
　　　　Return
　　End If

　　Dim bc As New FarPoint.Web.Spread.ButtonCellType()
　　bc.Text = "ボタン"
　　bc.CssClass = "CssStyle1"
　　bc.CommandName = "test1"
　　FpSpread1.ActiveSheetView.Cells(1, 0).CellType = bc
End Sub

-------------------------------
HTML
-------------------------------
<style type="text/css">
.CssStyle1 { font: bold large "ＭＳ 明朝"; }
</style>

------------------------
Webフォームクラス
------------------------
protected void Page_Load(object sender, EventArgs e)
{
　　if (IsPostBack)
　　{
　　　　return;
　　}

　　FarPoint.Web.Spread.ButtonCellType bc = new FarPoint.Web.Spread.ButtonCellType();
　　bc.Text = "ボタン";
　　bc.CssClass = "CssStyle1";
　　bc.CommandName = "test1";
　　FpSpread1.ActiveSheetView.Cells[1, 0].CellType = bc;
}
-------------------------------
HTML
-------------------------------
※VBと同じです