How to add Custom text box in light box

How to add custom text box/drop down box in event create light box ,and how to get those data in event save objects.

need to get those custom added field data in this objects.
scheduler.save_lightbox = function() {
var e = this._lightbox_out({}, this._lame_copy(this.getEvent(this._lightbox_id)));

console.log(e);
(!this.checkEvent(“onEventSave”) || this.callEvent(“onEventSave”, [this._lightbox_id, e, this._new_event])) && (this._empty_lightbox(e),
this.hide_lightbox())
}

Thanks
Midhun M S