I dont understand how they did the multitouch of the paddles on the different sides? Could some one explain it to me?

You just enabled multitouch - is that want you want to know, how to enable it?

If so, it's one line;
system.activate("multitouch")

Peach :)

I am trying to make a pong clone from scratch and I tried using the multiouch but the objects will disapper, I am using your code I think for moving the objects with your finger

There's actually an example of a pong game using multitouch on Techority you could work from. (You can still make one from scratch but learn from the example.)

See here; http://techority.com/2011/06/29/pong-in-73-lines

Peach :)