That was a good deal for the Nexstar and even if you need to replace something on it you are still ahead of the game.
As already mentioned DO NOT attempt to fly this at a park or at an area where there are others nearby not knowing what you are doing. This size plane needs to be flown at a club field or in a somewhat remote area AFTER you become good at flying it.
Take the advice , join the AMA, and find a club nearby.  I am sure someone in the club will assist you in going over the plane and properly instructing you in safely operating it and take you up with it until you get proficient at take-offs and landings on your own.
Please don't try and do it on your own.
Good luck and have fun !!