Hi, can anyone help with the following?:

I recently upgraded from an iPhone 4 to a 4s & the 4 was fully backed up to the iCloud prior to the exchange. Unfortunately the 4s then got damaged & had to be exchanged for a new one - a back up had taken place during this time so what I would like to know is how to retreive that data from the iCloud? I have read that there is an option to 'restore' old back-up but I can't find that anywhere!