1. Once you download the Zip file, double click on it. This will automatically create a folder in which contains the unzipped files. The folder will be placed in the same location as your original Zip file. If you need help finding your Zip file, open Finder and search for it.
1. You can also download a program called The Unarchiver 1.6.1 from Tigerware by clicking HERE and then clicking on download. The Unarchiver is a program used for unzipping files.
2. After you have downloaded The Unarchiver, open up the program.
3. Select to put a check mark by Zip Archive.
4. Now whenever you download a zip file, it will have The Unarchiver Zip icon.
5. Find the zip file you have downloaded and double click it. This will unzip your files into a folder located in the same location as your original zip file.
Referenced from: apple.com