It IS quite simple !!! Look in your utilities folder >>Drive set-up application >> Drive set-up guide. Read it, read it again, then print it out so you'll have it during the procedure.
Only 2 other things required to do partitioning.......A current, complete BACK-Up of the drive to be partitioned, and a bootable start-up disk, either a current OS CD, or Zip disk, or another bootable HD. Because in case you havent found out yet......partitioning erases EVERYTHING on your HD, and gives it a fresh start.
HTH