Why don't some of my sims 3 mods work?

I have the sims 3 base game and the mods that dont work are the ones that have been saved rather than opened first.I saved them because I have no idea how else to get them to work. I dont know what to do about this so any help would be greatly appreciated. thank you :)Why don't some of my sims 3 mods work?
1st You CAN'T open a mod file which i guess it's a .package file for the sims 3, in able to make the mods work you have to create a file in your sims 3 directory called "Mods" then in this folder create another one called "Packages" in which you place the mods.Don't forget that you have to download the ressource.cfg file to make the mods work, you can download it from google.



If you've done all these steps and the mods still don't work the files you've downloaded may be corrupted.