WebMethod in my webservice should return a dataset and yet returns an array?

    [WebMethod]
    public DataSet GetPopularFlavors()
    {            
        return Helper.PopularItems();
    }

    localhost.Statistics s = new localhost.Statistics();
    topItems.DataSource = s.GetPopularFlavors();

And just for the record, im kind of new at this so im really sorry if im doing something that is obviously wrong...