To find promo codes at Patpat, you can visit their website and check their homepage, sale sections, or sign up for their newsletter to receive exclusive codes via email. Additionally, you can follow Patpat on social media platforms, where they often share promo codes. To apply a promo code, simply add items to your cart, proceed to checkout, and enter the code in the designated field. Click "Apply" to see the discount reflected in your order total.