Unlike English, the Korean language has original form of verbs. When you put "ㄴ다", it makes the original form the present simple tense.
See this..
살다 : original form
But you have to say like "나는 한국에 산다."
사랑하다 -> "나는 가족을 사랑한다."
공부하다 -> "나는 영어를 공부한다."
If you have a Korean learning textbook, it is sure to explain more clearly about the Korean grammar.