I recently backed up my iphone 4 because I plan on buying the new iphone 5, and tried to locate the back up in my documents so I would know how to retrieve it when I get the new phone
There is no need to locate them.
Restore the new phone via iTunes using the backup.
When the new device is plugged in iTunes will prompt to setup as new or restore from a backup.
At the bottom of the article from which the question was posted was the following link http://support.apple.com/kb/HT2109 which explains how to restore a new iOS device with a backup from a previous device.