You should be able to craft it, once you have the carpenter’s bench unlocked, by doing the following:
- Place down the carpenter’s bench
- Access the carpenter’s bench and put some wood into it (let’s say, 50)
- Once the wood is inside the carpenter’s bench inventory, go to the right menu and select the option Shaped wood
- Once it is selected, you’ll see the requirements, and the option to craft 1 single piece, craft 10 pieces (if enough wood is present) or craft all the shaped wood allowed with the present wood in the bench’s inventory
That should do it. Once you’re crafting it, you can leave the bench until it’s done (it can take a while)