I agree, I should have improved the background but I was in a hurry to deliver it to my little nephew (he was asking me everyday if the painting was already finished...
I painted it in tones of yellow ochre/burnt umber.
I am a newbie in oil painting and never did a glaze. Glazing seems to be unknown here in Brazil (or at least not usual). I have read a lot about glazing and I think that brazilian oil paintings haven't enough quality to do this technique. I think to buy some oil painting from an international quality brand to do some tests soon.