You can't submit new words, unfortunately. 

And posting (off of the hearth) making threads and responding to questions are the ways now. 

No one can modify Dovahzul for now. We want to master Bethesda's language before going further

To get coins, play site games and post on the forum (not Hearth).

Or find somebody that is rolling in it, and try to impress them with your skill in the dragon language. If possible.

But games are your best bet. I got 245 gold in Forelnaar.