Pretty much any Android device nowadays running Ice Cream Sandwich is capable of being updated to Jelly Bean but as mentioned above, it still depends on your manufacturer.
The method is usually an OTA (over-the-air) update that requires you to have a wireless connection to be able to download the needed files to begin the installation. The best part is that there is no need to download miscellaneous tools to your computer to do the procedure, it's all done through your phone.
Jelly Bean 4.1 may look like just a small improvement of Ice Cream Sandwich 4.0 but the truth is, it can be considered a huge overhaul with dozens of new things added.
Important:Before you consider updating your device, make sure that it is properly charged because if your battery is drained out and happens to power off your device while you are installing the update, you might encounter some problems.
- Go to your menu/app drawer and from there head to Settings.
- Find the option that says About phone (if it's a tablet device it may say About tablet) (The option is usually found at the bottom).
- From there, look for an option that says System updates.
- You will be taken to another screen and this one also depends on what kind of device you have, but usually there should be a simple button that says to either download or install the update. Simply choose it and the procedure should begin.
- Your device will restart, install the update, then it should automatically boot to the updated system.