Hi there,
Digging can be a sign of a fertile female or brumation but given your set up and that he is in a new home the digging is highly likely to be because your dragon is seeking security and somewhere to hide.
I would definatly buy him a hide or alternatively you can make one very easily out of a cardboard box (i can post pictures and instructions if you'd like).
You are likely to have a much happier dragon that way ^_^
I would also look into buying a rock/branch/platform for your beardie to bask on directly underneath your lamp. This will help your beardie thermo-regulate between the hot side and cool side.
That substrate definatly looks like crushed-walnut which can be fatal for beardies so please get it out of there immediately. Until you get yourself a new substrate you can line the bottom with kitchen paper towel.
Just as Dragons1222 said your options for substrate are:
Tile,
Shelf Liner,
Repti-Carpet,
Washed Playsand.
Holly x