Eating well while working out to drop 40lbs

Hello all,

I had another post in the F&E section. I've dropped about 14lbs (from 252 to 238) by walking on a treadmill for 90 minutes (~7km) 3 days and doing Jillian Michaels 30DS dvd 3 other days.

My weight loss has lateaued since then and someone mentioned that I may not be "eating right".

What should my diet look like? My goal is to drop another 40lbs or so to go down to 200lbs (I'm 6 ft tall). I'm not entirely sure how much protein or carbs etc I should intake.

Thank you!