You can re-order your layers in three ways:
1- You can hover over an element's name in the timeline to display the [rearrange] button. By clicking and dragging you can move that layer up or down.
2- You can modify the element's [Style Z-Index] value. The higher the number, the further to the top the element will be.
3- You can use the contextual menu on the stage to move your element front and back.