나의(or 저의) 이름은 MJ입니다. na-ui(or jeo-ui) ee-rum-eun MJ ip-ni-da. This expression is formal. If you want to say informal, you can just say "나는 MJ야. na-nun MJ ya" It's kind of hard because there are many different expression to describe depending on the relationship and situation. However, hope it help you. Enjoy learning Korean,MJ. ^^