Crafting itself is simple to pick up -- just hit R and spend points in the crafting tree. You'll see that it is impossible for a single crafter to become an expert in more than one or two skills. The skill trees themselves are oddly split -- training in Swords and Axes gives you no abilities to create Spears and Polearms. Master the crafting of chest armors, but that will do you no good when it comes to making shoulders and helms. Focus on becoming the best cobbler in Uld, but don't expect that skill to carry over into the scribing of Heraldries.
Here is a brief overview of the crafting quests and the process of crafting itself. You can read a more detailed list of the benefits of crafted items over on the official Mythos forums.