That's like competing in a Nascar racing, without had never driven a car before.
Short films are the best film school. You learn so much from mistakes you make (and you WILL make them). You learn, you improve yourself, and you build a portfolio to showcase your work.
Unfortunately, new filmmakers have the dream of making a real movie.... now! You will put money, time, lots of work and other resources into something which result will be more than likely, a tragedy. Dont skip the learning process. Make short films first!