WebAPI Entity Framework problem

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations;

namespace Save4LaterAPI.Models
{
    public class SavedSites
    {
        public int Id { get; set; }
        [Required]
        public string URL { get; set; }
        public string[] tags { get; set; }

        public int OwnerId { get; set; }
        public User User { get; set; }
    }
}