public int CurrentRating {get; set;}

FarPoint.Web.Spread.Extender.RatingCellType rate = new FarPoint.Web.Spread.Extender.RatingCellType();
rate.StarCssClass = "ratingStar";
rate.EmptyStarCssClass = "emptyRatingStar";
rate.FilledStarCssClass = "filledRatingStar";
rate.WaitingStarCssClass = "savedRatingStar";
rate.CurrentRating = 2;
rate.MaxRating = 5;
rate.RatingDirection = AjaxControlToolkit.RatingDirection.LeftToRightTopToBottom;
rate.ShowEditor = true;
FpSpread1.ActiveSheetView.Cells[0, 0].CellType = r;

.ratingStar 
{
    font-size: 0pt;
    width: 13px;
    height: 12px;
    margin: 0px;
    padding: 0px;
    cursor: pointer;
    display: block;
    background-repeat: no-repeat;
}

.filledRatingStar {
    background-image: url(images/FilledStar.png);

}

.emptyRatingStar {
    background-image: url(images/EmptyStar.png);
}

.savedRatingStar {
    background-image: url(images/SavedStar.png);
}