Download and unzip WPReviewsite
Make sure you have saved the downloaded wpreviewsite.zip file, into a suitable folder on your computer.
Now extract the contents of this file
You can see the contents of the file. Now you need to move your mouse pointer to the "Extract all files" comand (1), and click on it.
Select a destination, where you would like the files extracted to.
I recomend that you accept the default folder, which will be next to your saved wpreviewsite.zip file. Once you are happy with this location, click on the "Extract" button (1).
You now have your folder unzipped.
It is time to decide whether you want to upload your plugin and themes manually, or through WordPress. I recomend that you become familiar with both proceedures.