Hi Tami-
Welcome to the forum and congrats on looking for a new bike! As for the Myka Specialized... the brand of the bike is Specialized, Myka is the model name. Specialized is one of the major bike brands out there and very respected among bikers. I ride one of their road bikes and love it! Myka is one of their woman's specific mountain bikes. I don't know which level of myka you are looking at specifically, but given that you said it was ~$400, I would guess either the Myka HT or Myka HT Sport. You can see a lot more on the bike on the specialized website: http://www.specialized.com/bc/SBCBkModel.jsp?sid=08Myka
While this will be a good bike, the most important thing when buying a bike is fit... so see about going into a bike shop, having them measure you for a bike and ride a bunch of different brands and geometries of bikes and see what you like!
good luck, and let us know what you end up deciding!