I hope you can understand the corrections this way... Two small errors. let me know if there is a word or sentence or phrase that you didn't understand! I will try to think more on the "since" question...
I went out to buy some food near the hotel. There were no supermarkets around and no food stores. The only thing I could find was a bakery with mass produced cookies imported from China.
Many thanks for your letter. I am delighted to tell you that I have passed my exams and am looking forward to the next year. Meanwhile I am planning a trip to Costa Rica and some places around there. | 
