I am not new to gardening. I have been at it for at least 65 years when My mom got all her kids working in the garden at about age 5. Yes I am 70 now so the raised beds do save a bit on the back.
My first raised bed in 2014.
Taught me I need to learn about tomato plant pruning as they grew to over 7 feet tall in the raised beds.
I also learned if I put the uprights on the ends I could put a cross piece in place and cover when there was a frost in the forecast and extend the growing easier than the old regular beds.
2015 I built the beds then lined the bottom with news paper to keep the grass and what ever from growing up in to the beds.
All the dirt came from back in my woods. It is all top soil from years of decaying leaves and other stuff found in the woods.

Al