第一天给老板英文邮件怎么说

你想问这句话怎么翻译？
还是想问这封邮件怎么写？

具体要看内容了，原则上就是礼貌到位，尊敬但不谦卑，把事情讲清楚，思路清晰，简明扼要，末尾不要忘记敬请领导过目（或批示）之类的话，最后署名写清楚你是哪个部门的谁谁谁。

Send a E-mail to my boss on the first day.

Today is my first day. I will hard work and show you, my boss, my performance and productivity.