Bought a classical guitar and need a major HELP?

hi, i just bought my first guitar which is a classical one! first of all i wanna check if it is tuned correctly, so i'm having a problem in tuning it. I have Garageband on my mac which contains an auto-tunner but the thing i think only the acoustic guitars work on it because when i select the low E string and try to tune it, the red bar stays at -50 and doesn't move even when i hit the string hard. if anyone knows a website where i can learn from bedrock the basics of playing on a classical guitar, please send me the link. and if anybody owns a mac and knows how to use the garageband tunner, please tell me how to use it for the classical guitar, i really appreciate all your answers. and i'll absolutely vote for the best answer and i wish that i can for more than one! OneLove.