I think this should help you out:
Try taking an art class or architecture class. The better you are at drawing your ideas, the better your chances at getting a job at WDI.
Now, if you ever wan't to create an idea, here's something to help you out:
Don't just have something pop into your mind and post it, give it some time to think about the idea.
Don't automaticly go to Disney Channel or Pixar for an idea.
Think as attractions not as rides or shows, but as an adventure that the average person can't usually expirience. Think of an expirience, and try making guests step back or forward in time to the era of your expirience, and make the theme fit well to the park you put it in, making it unique.
Try not to spare any detail in anything you create. Think it out from the expirience itself, the buildings, to the new shops and food areas around it that fit with the theme.
Once you do this, you will be able to master the art of Imagineering.