Since you were asking how to add live sand and not "is live sand good?", Id say take the bag of live sand and pour some into a bowl then lower the bowl to the bottom of the tank and slowly pour it out avoiding covering any area too much. If you keep your sand bed really clean and have a good skimmer you can agitate the sand bed after you add the new sand to mix it up and avoid dead spots from occuring If you have a lot of delicate corals or you know your sand is kinda gunky I wouldnt stir it up, but the lfs by me used to take a bag cut open a corner, submerge the whole bag and then cut the bottom so it just spilled out. It clouded up the tank for a few hours but by the next day the skimmer had taken care of it.
gl!!