The Writing Desk is crafted using five wooden planks, one ink sac and one feather:
The Writing Desk has one book slot on the parchment on the left and one book slot left to the text field. The first slot is for a Notebook, which you should just place and leave in the slot. As soon as you place the notebook into the slot, a page with all symbols you have discovered so far will open.The second slot is where you place Descriptive Books. If you have already visited the age the descriptive book links to, the writing desk will automatically transcribe the symbols from the book into your notebook.
You can use the text field to rename the book - this works for Descriptive Books as well as for Linking Books.
If you want to create your own age, you should craft and place a Descriptive Book into the slot on the right without having visited the age it links to - this is important. You can then choose from the symbols you have collected so far, simply add them with a Left-click.
Keep in mind, however, that when you visit the age, the game will automatically add additional symbols if it thinks that some are missing - so you might end up with a void world or a flat world if you did not choose your symbols correctly.
Video Tutorial Edit