According to the information given by you, you've probably accessed the Flame Forge in-game already, to try to forge a flame (if you didn't, press Ctrl+L).
To be able to forge actual flames, you need to buy the Flame Forger subscription, which can be found
here.
You'll need to pay to use it (monthly fee, which can be cancelled) and you will need to pay certain amounts of toricredits to forge the flames.