How do I update my iPad first generation without a pc?

You can't. Take it to a computer, possibly a display model at a physical store, and update it from there.

(79242)

The only way to update an iPad to iOS 5 is with a computer and iTunes. If you do not have that, use a friends or go to an Apple store genius bar and see if they will assist you with it.

Instructions once you find a computer to use.

If you have an iPad 1, the max iOS is 5.1.1. For newer iPads, the current iOS is 6.1. The Settings>General>Software Update only appears if you have iOS 5.0 or higher currently installed.

iOS 4: Updating your device to iOS 5 or Later

http://support.apple.com/kb/HT4972

How to install iOS 6

http://www.macworld.com/article/2010061/hands-on-with-ios-6-installation.html

iOS: How to update your iPhone, iPad, or iPod touch

http://support.apple.com/kb/HT4623

If you are currently running an iOS lower than 5.0, connect the iPad to the computer, open iTunes. Then select the iPad under the Devices heading on the left, click on the Summary tab and then click on Check for Update.

Tip - If connected to your computer, you may need to disable your firewall and anitvirus software temporarily. Then download and install the iOS update. Be sure and backup your iPad before the iOS update. After you update an iPad (except iPad 1) to iOS 6.x, the next update can be installed via wifi (i.e., not connected to your computer).

 Cheers, Tom 😉