Can I just put it in a Tupperware and leave in freezer? And when how what to use it again, what do I do?
You can't freeze unbaked batter; the acid-base reaction which provides your rise will complete, and the final cake will be leaden. You are better off baking it and freezing the cake.
The previous answer is correct -- many cakes freeze extremely well. Just be sure to let the cake cool completely and wrap it tightly in several layers of plastic wrap then a layer of aluminum foil. When you're ready to make the cake, you should move it to the fridge to let it thaw completely. Then decorate as usual.
Darn ok. Thanks.