I have downloaded the base sims 3 and I have had it for a while but now I want to download a expansion game (pets) what should I do?

I am usually good with all of this sims 3 downloading stuff but I just want to make sure before I do anything that I don't stuff my game up.
So I have the base downloaded from piratebay and I have been playing it for a few days. I now want to install the sims 3 pets (I know in the future I have to use the most recent games crack).
In my (program files) game bin do I just replace the crack (not sure if it's called the crack but it's the 2 files that I have to copy and replace) from the most recent expansion pack I'm using into there?
Also do I use the crack from that has been supplied to me with the download from piratebay or do I use the one that is in the fix that I downloaded from this site?

I don't want anyone to link me to that page because I don't understand it.
It says that I have to download a manual patch after I have downloaded the expansion packs that I want, don't the patches and everything come with the torrent I download?

Ugh so confused and I just want expansion packs.
If someone could explain to me step by step on how to get the expansion packs to work.

Hello,

Sorry, but I do have to link you back here: www.games4theworld.forumotion.com/t1171-must-read-how-to-install-the-sims-3-correctly

No, since we can not update the files that have already been uploaded as a torrent, we provide the latest downloads here. For example, if you download World Adventures or something, it comes with a heavily out-dated patch, which is of no use to you. The manual patch updates your game to the latest version and it replaces all corrupt and/or cracked files into their original state.

The 1.38 manual patch is currently present in the Supernatural torrent, yes, but if a new patch is released, that one becomes obsolete!