HELP recording sound in FRAPS Full version!!!?

i have the full version of fraps and i need to record sound from the game im playing. i dont wnat to put my microphone up to my speaker ause the sound quality is horrible. when i disconnect my microphone it records ver y very quite sound. i have to turn up my 1000watt home theater on max to hear the sound. how can i record good quality loud sound with fraps