可以这样写：
Dear Sally,I am sorry to hear that you are not felling well.I think you should believe yourself(相信自己).Then,I think that having convercation with others is a good way to improve your Chinese.If you feel terrble,for example you feel it’s diffcult for you to study,you can ask your teacher for some helps.I hope you can do better!
Best wishes!
Yours,
署名
【我的文章一直是满分作文,相信我!】
You can do better!