-I'm writing to tell you some relevant details about...
我写信是想告诉你关于……的相关细节
-I'm glad to receive your letter, and I'm writing to give you some suggestions on...
很高兴收到你的来信,我写信是想给你一些关于……的建议
-It's my great honor to be here and share my opinions about...
我很荣幸能在此,分享我关于……的看法