How to create a good program structure ?

What you want to do in situations like this is to declare and implement an interface. Both the player table and AI table will have features that are common, but might be implemented differently; this is where interfaces come in handy. You can even define a base class that implements the part of the interface that could be the same for both (such as Draw()).

Here's a quick sample of how that works, with a goofy psudocode snippet to show how to use it.

public interface ICardHand
{
   int Draw();
   ICardResult PlayCard(ICard card);
}

public abstract class CardHand
{
   public int Draw()
   {
      ... //logic to draw card
      return numberOfCardsInHand;
   }
}

public class PlayerHand : CardHand, ICardHand
{
   public ICardResult PlayCard(ICard card)
   {
      ... //get the card from the UI thread, etc
      return card.Result;
   }
}

public class AIHand : CardHand, ICardHand
{
   public ICardResult PlayCard(ICard card)
   {
      ... //perform card selection through voodoo and whatnot
      return card.Result;
   }
}

public class CardTable
{
   public IEnumerable<icardhand> Players { get; protected set; }
   
   public void Deal()
   {
      foreach(var hand in Players)
      {
         var count = 0;
         while(count < 7)
         {
            count = hand.Draw();
         }
      }
   }
   ...
}

Please bear in mind that I wrote this in 5 minutes with no context whatsoever. This is solely to show you how to code against an interface, not for use (I've had questions that required this caveat, which is why I'm giving it).

This also gives you the flexibility of adding options down the road. If you code against an interface, it doesn't matter if an AI is controlling it or a human. You could use the same code base to run a multi-player game as a single player one.

As for your last question, you should abstract your game engine enough that it doesn't matter how the assets are managed. This will give you options, in case you want to use a different GUI mechanism or need to change out the graphics due to system changes (such as DirectX version updates).

Anyway, just start thinking about how you can structure your game classes and how you want them to relate to each other. Boil it down to as primal of a structure as you can, and that will help you define your interfaces.

Best of luck!