A program that i can mix songs and make ONE song ? like a DJ program! freeee though?

VirtualDJ is a good program as is DSS DJ. However, if you want to make a serious pro-sounding mix, you might consider getting Traktor (some versions are free) or Ableton if you want to do more interesting things with your mix. Hint: mix manually. Don't use the beatsync as they're almost always inaccurate.