FFWDME.JS and GraphHopper

If you don’t know , FFWDME.JS is a javascript turn-by-turn.

I want to use it but it isn’t a routing service so it doesn’t calculate routes.
They told me to use GraphHopper routing service but I don’t know how to use it.

Anyone know how to work with FFWDME.JS and GRAPHHOPPER ?

Is it possible to create a json file lke this ?