Android: How to Make A Drawable Selector

I feel like this is kind of a silly question, but here I go anyways. I have an image button, and I want to be able to change it's image everytime it is clicked. The API seems to say that the best way to go about doing this is to create xml resource in the drawable folder that contains a selector and values. However when I go to make a new android xml resource, there's no option for drawables. What am I missing?