How do i update iOS 5 on my sister's iPod Touch 3rd Generation?

[DeeDee1]

I have an iTouch 4g, and my sister has an iTouch 3g. We both want to use iMessage, but only i have it. We tried finding ways for her to update to iOS 5, but can't. What to do? D:

 

[ColinGarrard]

So many who updated asked how to uninstall this.