To create and import quiz questions you need create and upload a text file that is formatted in a particular way. Here's an example file that you can use as a template. Just download the file and follow the two steps below to see how it works. You can get a good idea of how to create questions by viewing the example file, but here's a short video explanation which may also be of help.
Note that all questions submitted can be viewed by the web page admin. Also, while precautions are taken to secure this web site, all web sites are vulnerable to attack, and hackers may gain access to the data submitted.