You can't. Magic is the natural energy found in nature and the world around us. We work with it and impress our will upon it and send it out into the universe to bring about a desired change. However, magic has its limitations and works within the laws of nature.
It can't be used to change your gender, it can't be used to change your race, it can't change your species, you can't use it to control the elements or the weather, etc. It can't be used to reach unimaginable odds. As practitioners of magic, we must first learn to accept and understand its limitations and its basics before we can truly begin practicing or understanding it.