What do you eat to workout?

Hi Well, just when I think I am on a roll, oops not! I know that what we eat is as important as working out. I was working with my PT today and when we got to shoulders I just pooped out. I had nothing more to give and he said I am not eating enough complex carbs. Ok, I am still trying to get this protein thing and now I have to get this complex carb thing going What do you guys eat to workout? Is there a website and or book or something I can read to learn how to eat to accommodate lifting weights and such? I appreciate your help Take care, Kathy