Can I add iOS directly using my ipad?

Not if you are running iOS 4.3.3 as your tagline indicates. You must update with the latest version of iTunes on a computer. This explains how to do it, if you don't already know how.

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

To add to what Demo said, connect your iPad to iTunes, and it should prompt you to update. After it updates, future updates can be done under Settings > General > Software Update. The ability to update directly on your iPad was only added in iOS 5.0.