Rule of thumb is about 30 calories per kilo of body weight, 40 to 65% carbs, 15 to 30% fat & 15 - 30% protein. Hydration is important too - 4 to 8 ounces of fluid every 15 to 20 minutes. (Kilos to pounds, divide by 2.2)
Take in more carbs when training fast or long, less for easier sessions. Carbs appear in plants and by-products: fruits, veg, peas/beans, and grains, plus milk and joghurt.