Wow, bet they are soooo cute!
Seriously though, that is far too young for them to be taken from their mother, they should be with mum for at least another 2 weeks, if not longer.
Anyway, watch them after eating and drinking, if you see them circling or scratching in a corner, pick them up and put them in the litter tray straight away. Hold their front paws and make a scratching motion, it won't take long for them to get the idea. Cats are very clean animals by nature. (NO lectures about them pooing in your gardens please!)