I am Grace.
저는 그레이스입니다. 한국어를 열심히 공부하고 싶어요.
> "나는" is also okay, but if you'd like to add "요" in the end of the sentence then "저는" is more appropriate as "저" and "요" are both respect forms. "나" is more casual so it doesn't really go with "요". Plus, "한국말" is also okay but more native way of saying is "한국어". Hopefully this explanation is helpful enough for you, Grace, well done! :)