public class Company : BaseEntity
    {
        public string Name { get; set; }
        public virtual ICollection<User> Users { get; set; }
    }

public class User : BaseEntity
    {
        public string Login { get; set; }
        public string Password { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public UserRole Role { get; set; }
        [Required]
        public virtual Company Company { get; set; }
    }

public class BaseEntity
    {
        public DateTime CreateDate { get; set; }
        public DateTime ModifyDate { get; set; }
        public string CreatedBy { get; set; }
        public string ModifyBy { get; set; }
        public int ID { get; set; }
        public bool IsDeleted { get; set; }
    }