Dear Fiona:

Very nice to hear from you!很高兴收到你的来信！

I had a great time yesterday. Everything went right for me! I gave a lesson to (give a lesson to sb. 给某人上课) the students in Class A for Ms. Edna last night. 昨晚，我替黄老师(Edna)给A班的同学上课。Because she couldn't come here last night. She had something important to do.

I know you are always very busy. But please remember to give yourself enough time to relax.不过，请记得给自己足够的时间放松放松。(Joozone Note:remember to do sth. “记得做…”，to后面加动词原形。relax意思是“放松心情”。give??oneself enough time 给某人自己足够的时间。) From joozone.com.

Frankly speaking(= To tell you the truth/To tell the truth/In fact, 意思是“坦率地说/老实说/说实在的/事实上/实际上”), you are making progress. I am sure you will master(掌握) english someday(有朝一日/总有一天).

So please keep on your English study. And study hard. Because the harder you study, the more progress you will make!

Good luck in your English study!

Best wishes!