Different objects can be created at workbenches. There are alchemy labs where you can brew valuable potions and tinctures, workbenches for making bows, and anvils for blacksmithing. These workbenches are found every so often at various different places.
In order to create an item or a tincture, you will require knowledge of the special Talents Alchemy, Bowyery or Blacksmithing, a set of instructions from the recipe book, and the components listed there. Once you have collected and learned everything, find an appropriate workbench and select the instructions there. If your Talent Test is successful, the appropriate object is created and placed into the inventory.
Note that there are separate workbenches for each of the three talents.