Install power iso which is included in this installation in folder "optional install's" then folder "2-image mounting programs" or equivalent and mount each image 1-9 If you have experienced an issue that requires you to reinstall your copy of The Sims 3 and expansions, please be sure that you install your games in the following order to assure proper patching.
Note: new worlds like Riverview or Barnacle Bay can be added at any time since they do not change gameplay, i recommend waiting til all 9 are installed then proceed to optional install folder and view readme/s.