select approx half of right side of painting with marque tool- rectangle.
copy and paste into new layer.
once again duplicate and flip vertical.
postion , two halfs to cover left handside of painting.
gradient mask to blend.
Tree is hard brush black and make tree shapes. Use smodge for smaller brushes.
step 2 of 2
create shadow shape . postion approx middle of background.
To create didg. cut out two chrissie balls. one white, one red. keep duplicating to create pattern. CUt strip out of painting and wall to create stripes.
once happy with pattern merge didg and pattern and FREE TRANSFORM DId into correct holding position.