Press and hold any app icon on the page where the app's are you want to move until they all start to jiggle.
Now press, hold and drag the icon of the app you want to move to the very edge of the screen and hold it there for a second.
It will then, suddenly, move to the page that you held it adjacent to - assuming there's still 'room' on that page.
When you've finished, press the Home button to stop the icons jiggling.
Tim