How do you lose 20lbs in a month?

I'm 21 years of age 206lbs 71" I do 30mins on the tread mill and lift weights Mon-Fri. I'm taking a low calorie protein recovery shakes, I take jack 3D before my work out and a during work out supplement but I have a horrible diet. What can I eat and do more or less in the gym to slim down? I want cut at least 10lbs in a month.