There is probably a tourist office that covers that ski resort. You should contact them as they will probably have a listing service and/or website.
You can advertise on http://www.anibis.ch/fr/default.aspx
It is free (but you need to keep renewing it every two weeks), You can pay for placement if you wish. You should advertise in FR and EN.
You might consider getting a "dot ch" website name (that partially uses the ski resort name and adds the word chalet). You can put up a simple Wordpress page with photos and details (once again FR and EN).
You website might come up in searches and you can also send interested people there to see the chalet.