Sign her up for a basic obedience class ASAP. Make sure you meet the trainer, observe a class, talk to past clients and get references (there are some evil trainers out there). I have no idea where you live and only know of trainers in my state (MA) which I am happy to list for anybody interested. Good Luck with the new girl
Some GREAT books that will help you to show her you are in-control but without the use of any force or violence are: "The ABC's of Positive Training" By Miriam Fields-Babineau, "Leader of the Pack" By Nancy Baer and Steve Duno, "Be The Dog" By Steve Duno, "The Dog Whisperer" & "The Puppy Whisperer" by Paul Owens and Norma Eckroate as well as anything by Victoria Stilwell. While it is VERY important for your dog to respect you, don't get sucked into the thinking that you cannot love or be nice to your dog. I once overheard a trainer telling somebody "Don't be nice to him or he won't respect you" ... that is furthest from the truth. Dog's are more responsive and more likely to listen to a calm and kind leader NOT one who uses intimidation to get his point across.