How to replace soil where we lost a tree

Hi! We recently took down a dead tree and ground out the stump. We left the stump wood chips in place to decay, but still need more material to fill in the depression left by the tree. It’s my understanding that I need to add actual soil – not just do a ton of lasagna mulching etc.

1) Is that accurate? 2) What kind of soil do I need? 3) Do I need to buy soil somewhere or is there a better way – like create my own using sand somehow?

Apologies if this is a dumb question – I’m just a couple years in to gardening and just now starting to learn about ecosystem balance and soil health!