If you have selected to sync Documents and Date in System Preferences, iCloud, your documents should appear in your iCloud section of Finder a short time after you update them on your iOS device. The document has to go from your iOS device to the iCloud server and then to your Mac before you will see them, so you need good connections to the web and a bit of patience.
In further support of Jerrold's response:
We assume the following:
- Your iCloud System Preferences on the Mac have Documents & Data selected
- Your iCloud settings on the iPad have Documents & Data enabled
- You have selected iCloud from the open dialog toolbar in Mac Pages
- You have selected Use iCloud from IOS Pages settings
- You have a reasonable network connection
I can open IOS Pages (1.7.1) to the available iCloud documents. On the Mac side, I open Pages v4.3 and pick an arbitrary .pages document, make some changes, and save it back to iCloud. On the iPad, I can watch a progress bar update that document icon within 5 - 10 seconds on the household network. I could do the reverse, and observe a OS X Pages document update as changes are made to the same document via iPad and iCloud.
None of your documents pop-up on the iMac like they do on your iPad/iPhone because the IOS operating system, and the IOS Pages application are significantly smaller and less demanding on the hardware than their counter-parts on Mac OS X.