How does a forge get lit? I've reread HS twice and the best I can guess is that Echidna lit it once Jade talked to her?

You light the forge by dropping the Queen’s rings into it. If you meant stoke the forge, well that’s not entirely clear. Davesprite says “ so jade must have done something right, to wake [Echinda] up and get the forge going, dont know what she did though” which could mean you need to wake Echinda in order to stoke it or that Echinda will just wake up when you do. We just aren’t sure.