Just placed my first ever sports bet based on KOS pick. glgl us

Im sorry for such a rudimentary question but i placed my bet on bitbook. national ml is -166.7, so i placed a .01 btc bet to win .006 btc. can u explain what the -166.7 means. again sorry for being such a nood:)

KOS, would u mind if i post my results in ur thread as a way to keep myself updated?