For those Mac Users that got oriented with the windows keyboard, you will definitely be loss in the mac keyboard as some of the windows keys are not available on the mac keys. For example is the page down and page up. It's not included in the Apple keyboards as well as those included on a MacBook, MacBook Air, or MacBook but, this doesn't mean you can't page up or page down on apple keyboards.
There's a simple workaround on how to page up and page down on a apple mac keyboard, and you can learn how to do that below.
How to Page Up & Page Down on Mac Keyboards
Page Up with Fn + Up Arrow
The “fn” key is at the lower left of all modern Mac keyboards, and when you combine that with the Up arrow, which is found on the lower right of the keyboard, you will perform the equivalent of a page up.
Page Down with Fn + Down Arrow
Paging down is done the same way as paging up, using the same “fn” key and the Down arrow to perform the equivalent of a page down on a Mac keyboard.
This is the same on all Mac keyboards, including the Apple Wireless Keyboard, the MacBook Pro keyboard, MacBook Air, and MacBook keyboards. The Apple Extended Keyboard has dedicated Page Up and Page Down keys, but this Function+Arrow trick will still work on that keyboard as well.