A beginner question: How should I care the wooden bars?. Should I use some kind of oil or wax?.
Thank you in advance.

Jesus,

It is a good idea to keep the bars free from dust. Keep the instrument covered when not in use. Make sure your cover is not heavy because it is possible that the weight of the cover can make the bar rails sag over the years. For cleaning the bars use a very light coat of lemon oil. You can buy this at any hardware type store. Careful not to use too much, and follow the directions on the bottle.

Hope that helps and good luck!
-Matt