Transfer purchased apps to iTunes library

While updating iOS on my iPad how do I transfer the purchased items to the iTunes library ?

In the file menu there is the option to do just that, transfer purchases, just click on it with the iPod connected and it will automatically back them up to iTunes, and sync them each time you reconnect.

Thanks Kevriano, while trying to transfer apps to iTunes library there was a network connection time out. Its asking me to ensure that the network settings are correct and network connection is active. Let me know where can I set it and try the whole thing again. Thanks... Hey btw it is an iPad

You won't lose anything. Before you do the update do a sync. Then everything backs up. Then you can do the update.