In Edit [1] ribbon you have Order [2] option. Order "To Front" [3] will put your element the last on the page and it will be on top of every other element. Order "To Back" [4] will move your element to first position witch will move your element under every other element. Order "Step Up" [5] will move your element one position down in the "List of page elements" while order "Step Down" [6] will move your element one position up.
Note: Please remember that in the list of Page Content the elements on the buttom are the last ones added so they will be on top of the previous added elements.