OK. Sorry you're having problems.
There should be two 'The Sims 3' folders on your computer.
You usually will only work with one of them and this is the one we usually refer to when we say to do something in the Sims 3 folder. That one, by default, goes into you Documents folder. The other one is in Program Files (x86) folder and you will probably never need to touch it.
You will need to launch a new game to get a new The Sims 3 folder in Documents.
If you want to add mods you'll need to shut down that new game once the new Sims 3 folder has been generated.
The mods folder goes into the Sims 3 folder in Documents. You have to put it there. The game won't make it for you.
