Rowing and free weights.

hey guys, i’m trying to get into shape now that i’m home for the summer before i go back to school. i am kind of ignorant when it comes to training and i am trying to tone myself up. i was looking into rowing machines because i hear they are great for cardio and use many muscle groups. would a rowing machine be a good investment? i am not looking to beef up, i just want some definition and want to be "in shape." i feel like a rower would give an intense body workout and i know quite a few crew members who are beasts haha. i am a pretty lanky fellow, 21y/o 5′6 135lbs. i also have free weights- dumbells and barbell with about 100lbs of weights. what could i do alongside rowing to work on other muscle groups?

i know diet is half the battle, but i think i pretty much have that covered. any feedback would be greatly appreciated. thank you.