Dear Wang Lu,
How about your life? Im writing to thank you for your warm reception during my visit to Beijing this summer holiday.(感谢的原因)
During the visit, I stayed at your home, and you cooked three delicious meals for me. And you showed me around quite a few places of interest, such as the Great Wall, the Forbidden City and the Summer Palace. Besides, you took many beautiful photos of me. Whats more, you went shopping with me. I really had a wonderful time. Another thing that I should mention is that your parents were so kind to drive us. (具体帮助的细节)
Thank you for your kindness again and give my best regards to your parents.(再次感谢)
Yours sincerely,
Li Hua