The definition of control here, however, differs...it's best to not shadow over what the elements truly mean in the craft.
For some, when we invoke certain rites and rituals, we may ask for the guidance and overseeing of the elements that comprise our world.
The pentagram is a symbol of the unity of the world's prime elements: Fire, Water, Air and Earth. Together, bound by the Spirit, they create the idea of the soul and it is the use of our soul that makes Magic possible.
While it is true that such things do not directly exist in this plane of existence, that does not mean we do not influence them. Often times, man uses the elements without even knowing it.
For instance, one of the basic tools of our trade, incense, is a conjoining of Air, Earth and Fire. Earth is represented by the herbs, chemical process and materials used to make it. Of course, Fire, is the ignition source and then the smoke and scent that exhume from it, is representative of Air.
The Chinese Elements expound greatly on this ideal, but that is a different realm of understanding I won't cover here.
There are other many ways of using the elements. Everything from divination to the crafting of brews and tools for use. In this way we can "manipulate" the elements, but it is more of an understanding and bond we have with the physical world, to achieve things in the spiritual world.
Perhaps you would enjoy diving into the more literal application of the practices, such as pyromancy or hydromancy, which is the practice of divining events and energy through the element in it's most base form. A lot like looking through a crystal ball.
I hope this has been more useful.