I'm sorry it took me a while to get back to you on this, but you misunderstood my post.
This code can only be used on the product page itself to trigger the add to cart form to submit the default buy now info, which is quantity 1 of the product with default options - it makes no difference what you put between the A HREF tags. The text inside the link tags can say *anything* in place of IMG TAG OR TEXT LINK. It could say "Buy Now" or "Add to Cart" or have an image there.
If you want to add a product to the cart from another page, you would use the code:
where productid equals the id of the product you want to add to the cart.
I hope this makes more sense.