package mods have no home!

[Cassie]

You have to create one manually.
Go to Program Files > Electronic Arts > The Sims 3 and create a new folder called Mods. Within the Mods folder make another folder called Packages. This is where your downloads will go.
It's important you go through Program Files and NOT Documents - it won't work that way.

Or you could just download this Install Helper Monkey [though I'm not a fan of it personally] and it'll send your downloads onto the appropriate location automatically.

http://www.modthesims.info/download.php?t=344611

Good luck.