Make Update to a live iPhone app

I have an iPhone app which is aleready live on the app store...Now I want to make small updates to the app (fixes and adding iAd)

How do I submit the new updated app..Will that create a new version OR is that not required?

Also in iTunes Connect, I do not see any link which says Submit update or new version..

Do I first have to upload via Loader ...Please guide me. Thank you.

You should update the "version" field in your .plist, then submit a new binary.

In the application page, there is a "Add Version" button in the lower right corner, as follows:

Click "Add Version", clarify what is being updated/fixed/upgraded in the new version, make sure that all the other fields are correct, and then submit.

After that, you will have to use the Application Loader (Mac App) to upload your binary.

No matter how small or insignificant the updates are, you have to add a new version. Note that the current version will not be removed from the store, so you will not lose sales (or downloads).

Also, note that while there are technical ways to slightly circumvent this (e.g., by downloading dynamic code from the internet), such practices are strictly forbidden and will cause your app to be rejected.