Sprinkle their regular food mix generously around the nest and all over their cage, the little ones will wander around to begin to pick them up, pouch, and nibble on them. You can also chop veggies into small pieces and maybe small bits of scramble eggs and slowly introduce them to fresh food. Porridge or baby food like Polar White said are also very popular with the pups and mum.
As they begin to eat more solids on their own, mum will wean them on her own, so no need to worry.