Relations between tables - ASP.NET CORE MVC

Hi,

 I need your help again. I have a project in ASP.NET that I have to read data and put this data in a database.

This is done.  The problem now is to relate these two tables.

I already made the relations in SQL Management Studio, but here in the project they don't work.

Explanation of the project:

One product can have more than one description.

So the descriptions must be in a different table

Now I will put the examples:

XML:

<products><product><id>100</id><name>Ball</name><price>15</price><quantity>2</quantity><description><comment>aaa</comment></description><description><comment>bbb</comment></description></product></products>

MODEL:

[Table("Table")]
    public class Product
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public int Price { get; set; }
        public int Quantity { get; set; }
    }
   [Table("Comentario")]
   public class Comment
    {
        [Key]
	public int Id {get;set;}

        public string DescriptionComment { get; set; }
    }

CONTROLLER:

private List<Product> ProcessImport(string path)
        {
            XDocument xDocument = XDocument.Load(path);
            List<Product> products = xDocument.Descendants("product").Select
                (p => new Product()
                {
                   Id = Convert.ToInt32(p.Element("id").Value),
                   Name=p.Element("name").Value,
                   Quantity = Convert.ToInt32(p.Element("quantity").Value),
                   Price = Convert.ToInt32(p.Element("price").Value),
                }).ToList();
             List<Comment> comments = xDocument.Descendants("description").Select
                (t => new Comment()
                {
                  DescriptionComment= t.Element("description").Value
                }).ToList();
            foreach(var product in products)
            {
                var productInfo = db.Products.SingleOrDefault(p => p.Id.Equals(product.Id));
                if (productInfo != null)
                {
                    productInfo.Id = product.Id;
                    productInfo.Name = product.Name;
                    productInfo.Quantity = product.Quantity;
                    productInfo.Price = product.Price;
                }

                else 
                { 
                   db.Products.Add(product);
                }

                db.SaveChanges();
            }
             foreach (var comment in comments)
            {
                var commentInfo = db.Comments.SingleOrDefault(t => t.Id.Equals(comment.Id));
                if(commentInfo != null)
                {
                    commentInfo.Id = comment.Id;
                    commentInfo.DescriptionComment = comment.DescriptionComment;

                }
                else
                {
                    db.Comments.Add(comment);
                }
            }
            return products;

            
        }

Does anyone have any idea how this is done?

Thanks for help me!