I think Tom means the “second” wa in “watashi wa” uses the particle “ha” indicating the subject. So here’s one way to write the same thing (all in kana).

はじめまして、ジョウダンです。どうぞよろしく。わたしはにほんごのがくせいです。

Or instead of douzo yoroshiku, you can say yoroshiku onegaishimasu.

You did very well with your introduction.

ようこそ！