How can i reactivate itunes after uploading iphone operating system 5?

Go to google. Next, search (4.3.3 download iPhone 4). Download the file. Should be around 600 mb. When it's done, go to iTunes. Then, plug in your iPhone. Now go to -----s IPHONE on the left. Where it says "update", hold "SHIFT" and click update. Now look wherever that file downloaded to. Select that file. Now iTunes will update your iPhone to 4.3.3