Are you looking something like that?
const { map, picker, utils, broadcast, store } = windyAPI;
const customIcon = L.icon({
iconUrl: 'wPin.png',
iconSize: [18, 18],
});
const markerOptions = {title: "myPoint", icon: customIcon};
const marker = new L.Marker(**[lat**,**lon**],markerOptions).addTo(map);