Forging ingame is free yes. The only cost that you will need to pay is to forge the flame. That's in TC.
To make money from that you will have to forge a flame, then take a few screenshots of it. Make sure you save the flame by pressing Forge ingame, and then save the web page link. You can create a sale thread under particle textures in the items board. Make sure you show the screenshots of the flame and the price you'd like for it.