Download the rar or zip files from my site and save them to your computer. Right click on them and using a program that handles archives extract the sims3pack or package files from the archives. To install them read 2.
Programs that handles archives: A free one is 7Zip.
How do I install the custom content into my game?
Sims3pack - install by double clicking on it after extracting. The launcher will open and the file will install automatically.
Package - Some of custom content is in .package format. You can install them the easy way, using TS3 Install Helper Monkey - details there.