Dear（对方的名字）:
I am very glad to learn that you have been promoted to the general manager.Congratulations to you on your success! When I know about this good news,I was so very,very pleased from my heart ,and as your old classmate,I was gratified by your success.
You are always smart,capable as well aspositive.I trust thatyou will be a man to accomplish great things in your new position.
Finally,I want to saythat you are a good example of me.I will try my best to workhard and get promoted by my self one day.
sincerely,（你的名字）
PS：鄙视楼上直接用电脑翻译还说自己是学生的…… 我是纯手工的哦~望采纳~