Sims 3 custom content (sometimes referred to as Sims 3 downloads) comes in three file formats:
You should make sure that you are downloading from a reputable site and that what you are downloading is compatible with your version of the game. When you download custom content, the files are likely to be archived (sometimes referred to as "zipped") and you'll need special software to unarchive (extract) them. You likely have this unarchiving software already installed. Important: Files for The Sims 2 are not compatible with The Sims 3. You should only be using files made for The Sims 3.
The .sims3pack, just double-click the file and the game will take care of the rest. It does take longer than unzipping all your downloads and moving all files at once, but the good part is that automatically installs it (and ensures the files are in the right folders).
Once you've unzipped the file you need, you move the file to your SavedSims folder and open the game. Where's the SavedSims folder? Look here:
- Windows Vista/7: C:\Users\(username)\Documents\Electronic Arts\The Sims 3\
- Windows XP: C:/Documents and Settings\(username)\My Documents\Electronic Arts\The Sims3\
- Mac OS X: /Users/(username)/Documents/Electronics Arts/The Sims 3/
Oh, if you don't have a folder called SavedSims, you can just make one and put the file(s) in there. Easy!
The .package files have to be installed manually. That's if you do not have the TS3 Install Helper from <a href="http://www.modthesims.info/download.php?t=344611">Mod The Sims</a>. With this software, you double-click the file and it will install itself automatically. If you don't have that helper program, it gets a little trickier. Find you The Sims 3 folder (see path above) and create a new folder called Mods. Your files go inside the Mods folder. There are dependencies if you use these .package files and you should brush up on the <a href="http://thesims3cheats2012.blogspot.com/2012/05/resourcecfg-file-new.html">dependencies</a>.