What size ski should I buy if im 6'?
Longer skis will make you go slower, shorter ones will make you go slower & enable you to do easier tricks. However, longer skis are pretty awkward. Try asking the ski shop when you visit them or calling, if it's an online one, to get some professional advice. I had friends use 160's who were about six foot, but I haven't ski'd myself in more than a decade.
you just need to go to your local dealer and look at the skis they have. find they guy in charge and find you a good pair of skis for you ability level. then look at the sizes they have. you will probably be about 169 ish. you want the ski to go between you chin and your nose.