Unfortunately a web search turned up two "P706" tablets. Can you give us any more information, such as screen size, or from Settings > About, which we could use to identify which you have?
However, what are you trying to do? If it's an OS update, you can probably find it by turning on WiFi and going to the Software Updates menu (look in Settings > About). If there isn't an update you can download there it's unlikely there is one elsewhere; android updates (like all mobile device OS updates) have to be built for the particular device, which is the responsibility of the manufacturer. Hence if the manufacturer has not distributed the update over the air (the normal way) it's unlikely that there will be one that can be installed via SD.
(For many devices enthusiasts build their own OS updates, called "custom ROMs", which can be installed if you "root" the device. Not everyone wants to get into hacking the software like this though, and it's generally popular devices for which development communities exist - a more obscure, off-brand device is less likely to have this option. Just saying that as I don't want to get hopes up. You'll definitely need to identify the device before you can investigate this option).
