Here are the steps I took to Find and Replace a word with a word(s) in Pages app for iPad:

 - Tap in the toolbar and tap Find in the popover.

 - When the search field appears at the bottom of the screen, type in the word(s) you’re searching for. The results are immediately highlighted in the document. Use the forward and back arrows to move through the document to see the results in context.

 - To replace the found term, tap (gear) to the left of the search field.

 - In the popover, you can refine your search by searching for matching cases or whole words only. Or, simply tap Find and Replace and a second text field appears to the right of the search field.

 - Type in the replacement word and tap Replace. Pages for iPad finds the first instance of the word and replaces it. Tap the forward and back arrows to find each instance and manually replace it by tapping the Replace button.

 - To automatically find and replace all instances of the word, tap and hold the Replace button until Replace All appears in the popover. Tap it and all the found words are automatically replaced.

For a graphical representation of the steps mentioned above, check out this article which I found useful: 

[Find and replace in Pages for iPad][1]


**Source: my.safaribooksonline.com**

  [1]: http://my.safaribooksonline.com/book/hardware-and-gadgets/9780132616645/working-with-text/ch05lev1sec8