ASP.Net Error: namespace cannot directly contain members such as fields or methods

CS0116A namespace cannot directly contain members such as fields or methods

using LifeNstyle.Access;
using System;
using System.Linq;
using System.Web.ModelBinding;

namespace LifeNstyle
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }
    }

    public IQueryable<Product> GetProducts([QueryString("id")] int? categoryId)
    {
        var _db = new LifeNstyle.Access.ProductContext(); 
        IQueryable<Product> query = _db.Products; 
        if (categoryId.HasValue && categoryId > 0)
        {
            query = query.Where(p => p.CategoryID == categoryId);
        }
        return query;
    }
}