confused about net calories

Can someone explain net calories to me or give me a link that will help me understand? My calorie goal is 1340, today I've eaten 754 and burned 421my net is only 333. So my question is should I be trying to get my net up to 1340? I never eat my excerise calories back and for some reason never paid attention to my net calories, how I'm wondering if I'm eating too little.