Hello and welcome to Android Forums. Hopefully I can help you with your problem.
First off, you need to check with your carrier and make sure that update in question is available for your device. If it is not, I recommend joining Android Forums, looking in the section for your device and see if any of the developers in that section have successfully ported a ROM with the Jelly Bean update to your device model. If your device is relatively new, there's a good chance there may be a custom Jelly Bean ROM for your device.
Best of luck and I hope you find a Jelly Bean ROM for your device.