Help with Eating/Exercise

HELP!  I started a fitness bootcamp this week and I need help with eating so that I can finish the 1 hour workouts. Today was our 1st workout and I passed out about 40 minutes into it. What do you eat to fuel you through a workout?  I ate 1/2 a banana before I started.  I really really want to finish this 6 week camp but I can't keep passing out.