You could go to Primary Forging Master in Carefree and Wu Long Village to learn and upgrade Manufacturing Skill. Buy recipes and materials from Primary Forging Master and forge weapons when you have enough material. You will get some forging EXP while carrying on your work. When your EXP is full, system will remind you to upgrade your skill, and it requires certain amount of money. When you're qualified, you could go to the advanced forging master to learn higher level forging skill.