my ipod does not provide software upgrade under general setting? where do i go

Then do it by iTunes if it can be updated.

iTunes 10 for Windows: Update and restore software on iPod, iPhone, or iPad

A 1G iPod can go to iOS 3.1.3

A 2G to 4.2.1

A 3G to 5.1.1

A 4G to 6

Identifying iPod models

Connect your iPod to your computer. Open up iTunes. Go to your device, and press check for Software Update. From there you will be told if you can get a Software Update, and will have the choice of updating