Hello d00m, as much information about the device as you can provide would be helpful. At least a name or processor type.
Not all devices are able to be updated from the Android they shipped with to the latest Android. The way Android works, is that each new version of Android has to be specifically made to run on certain hardware. If your device manufacturer didn't build an updated version of Android for your specific device you will not be able to update. Even then it would be unlikely that your device has an update to the latest Android. Most tablets running Froyo will never receive an update beyond Gingerbread if they even get that.
Your best hope for being able to update is if you have a certain hardware set that is supported by developers who make custom ROMs for it. If you are lucky and that is the case for your device you may be able to find a custom ROM all the way up through Jelly Bean but it really depends on the developer community for each device.