First of all, have fun planning! Don't get too crazy about every detail and remember to have a little flexibility in your plan. Start by looking at a map of Disney World. Search on the links listed on top of the forums page. DISboards has all the maps you'll need. After you get a feel for how big the place is, start reading all the great info you can gather. If you don't know were to stay, the Resort Forum and also the Resorts link on top of the page will give you descriptions and pictures. Set your budget and book a room!
I usually make an excel spreadsheet to use as a day by day organizer, but a piece of paper works well too!
Ask all the questions you have on the boards and someone will have your answer!