Apple has churned out iOS 4.3.3 update for the iPad 1 as-well-as for the iPad 2. There is nothing new added in this update and the only thing it patches is the location bug that was found in iOS 4.x earlier.
To perform the update, connect your iPad to your computer and fire up iTunes. You will see a message telling you to update the firmware of your iPad. Just follow the onscreen instructions to fetch it from Internet and install it on your iOS device. However, for jailbreak, you will need to get hold of the IPSW file (firmware file) itself and here are the direct links to those: