Try out a build yourself!
About the “1×6:” This is simply what the piece of lumber is called, and it’s named for it’s measurements. Go for a pine board if you have access to it- it’s the least expensive.
This is a 1×6 board from Lowes: https://www.lowes.com/pd/Top-Choice-Common-1-in-x-6-in-x-8-ft-Actual-0-75-in-x-5-5-in-x-8-ft-Pine-Board/1000601717
This is a 1×6 board from Home Depot: https://www.homedepot.com/p/WeatherShield-1-in-x-6-in-x-8-ft-Ground-Contact-Pressure-Treated-Board-253935/206974075
These are the hooks I referenced: https://www.amazon.com/gp/product/B07KS2D3JB/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1