it depends... you got to dig!! start with a simple piece of music, like a piano on an old jazz record/cd/tape/etc., and loop it, change the pitch, apply filters, just play with it. the best advice here is practice, practice, practice.... dont try to hard at first; be basicwhile you are learning. what do you use? if you have an mpc you can really play with the basics of this. i am not familiar with too much software... im a drum machine guy myself. so the things you do depends on what you use. you can chop a long sample into 2-3-4 pieces, assign them to different pads and pound away until you come up with a new melody... also i would recomend learning step recording if you own a drum machine.... it takes a bit to grasp, but it makes a world of difference.