Yes, do get yourself a map. There are plenty of really good maps and even better map apps for Manhattan and all 5 boroughs. Also, you can get apps for the subway as well. I suggest that you get the stable apps, ones that don’t require Wifi. (I’ll discuss Wifi later in the series.) Though many of the subway stations now have Wifi.
Much of Manhattan is on a grid pattern till you venture below 14th Street. The avenues (Fifth Avenue, Park Avenue, Madison Avenue etc) are North/South streets. The numbered streets (42nd Street etc) are East/West. Which makes it a little easier to figure out which direction you are going.
Manhattan is not aligned with True North, but it's close. So in the morning you'll see the sun come up on the East River and set on the Hudson River.
Give yourself a little time to get situated. Don't worry, be happy! It's your vacation after all!