Here is a quick tip to set password options for pages files. It may not be something you want to use often, but it is an overlooked feature that can come in handy when you need it.
It is really very simple. Just open a document and in the inspector window choose the "require password to open" option.
The rest is pretty self explanitory. You will be asked to type and verify a password as well as give yourself a hint. I recommend the "hint" option as you will be up a creek if you forget the password you gave the document.
Below is a screen shot in case you are having trouble findin the right tab in the inspector window.