beginning
こんにちはわたしはショーンです。はじめまして。どうぞよろしくおねがいします!
I would change it to
はじめまして、わたしはショーンです。
よろしくおねがいします!
Hajimemashite means "it is the first time I meet you" so you don't need konnnichiwa here.
And it is also more common to say yoroshiku onegaishimasu than saying douzo yoroshiku onegaishimasu in this sitation, but I am not 100 percent sure on that.