How to tell a boy and a girl box turtle apart ?

I found a small turtle in my backyard and wanted to keep it as a pet. I put it in a big card-board box with mulch, a big rock, and a water and food bowl. I put water in the water bowl but didn't know what to put in the food bowl. So i thought.....I volunteer up at the local Good Zoo and i make diets all the time for the Egyption Tortiose and it eats celery, apples, carrots, etc. I made all of that and put it in the box. The next morning I went out to check on the turtle and it tipped the water bowl over and didn't eat ANY of the food.....I was really woried....soooo I kept thinking of things...I didn't know what kind of turtle it was so i typed many species of turtles in and i kept looking at the images on google and found out that it was a box turtle...so the next thing I wanted to know is if it was a male or female?.....and what it eats in the wild? So if anyone can help me find out if it's a male or female and what it usually eats in the while I would be really pleased....and PLEASE NO STUPID OR GOOFY ANSWERS!!!!! :) Thanks!!