To purchase Kiehl's products on GiftPattaya, follow these steps:

1. Visit GiftPattaya.
2. Go to the "Health & Beauty" section.
3. Select "Perfume" or "Cosmetics" from the options.
4. Search for Estée Lauder products within the listed items.
5. Choose the desired Estée Lauder product and add it to your cart.
6. Proceed to checkout and follow the instructions to complete your purchase.

If you cannot find Kiehl's products, use the search bar or contact customer support for further assistance.