I need help!! I've downloaded a few of the sims from the site and want to install them into the game. How do I do it? I'm a little confused as to which files need to be installed and which ones will be picked up by the game automatically.

In order to better solve your problem, please go through the following as listed below:

• Sims 3 - Installing Custom Content
  You appear to not have read our great guides to downloading and installing custom content for Sims 3.
  
  Game_Help:TS3_Custom_Content^wiki This link contains everything you've ever wanted to know about installing .package and sims3packs.
  

On occasion you might be asked to do a long FAQ - please make sure you do all the steps and don't just skip over them. You'll often find that these long FAQs have all the details you need. If nothing in the above FAQs fixes your problem you may post again detailing exactly which you have done and which steps failed.

I have read all the guides but it's still not working. The files are package files but sim files and so the programs aren't working for them and they're not showing up in the game.

Thank you for the help

if they're .sims3 ones (ie, the ones with the plumbob logo), you just double click them and the launcher will open and install them. you don't need any external programs or to move them anywhere.