Well Kevin, there are so many things you can do at Disney World that it'll be hard to fit into one response but I'll do my best.
WDW is set up into 4 major theme parks. These include The Magic Kingdom, EPCOT, Hollywood Studios, and The Animal Kingdom. I'll break these down for you:
The Magic Kingdom
-The most popular and iconic park. When people think Disney World, thoughts of The Magic Kingdom are not far behind.
-The park is split up into five subsections. These include Main St., USA,Frontierland, Adventureland, Tomorrowland, and Fantasyland.
-Here you'll find some of Disney's flagship attractions. These attractions include, but are not limited to, Space Mountain, Splash Mountain, Big Thunder Mountain, The Haunted Mansion, Pirates of the Caribbean, and Peter Pan's Flight. While these rides are some of the most fun, hefty lines are to be expected. Depending on when you visit the resort, lines for these attractions can range from 30-100 minutes. Don't fret though, as there are plenty of rides that are just as fun, without such long lines. Some of these rides include Buzz Lightyear's Space Ranger Spin, The Mad Tea Party, The Astro Orbiter, The Tomorrowland Transit Authority, The Carousel of Progress, and Dumbo the Flying Elephant. While these rides aren't as thrilling or popular, they still provide elements that will complete your experience at The Magic Kingdom.
-The dining at The Magic Kingdom is probably my personal favorite out of any of the parks. The most popular restaurants include The Crystal Palace and Cinderella's Royal Table. Both of these offer great food as well as the chance to meet characters. At The Crystal Palace you'll come across characters from the Winnie the Pooh universe including Eeyore, Piglett, Tigger and the honey bear himself. At Cinderella's Royal Table you'll likely meet a seemingly random selection of princesses as well as Cinderella's mice and her Fairy Godmother. However, The Magic Kingdom also offers a great selection of quick dining. At the corner of Main St., USA, you'll find Casey's Corner which is an excellent place to go if you're looking to get a quick bite to eat. It's a very old fashioned style where you'll often find a piano player sitting outside tickling the ivories. There are also a multitude of carts you'll come across that serve anything from hot dogs and pretzels to Dole pineapple Whips.
-The Magic Kingdom also offers a wide variety of character meet and greets. Off the top of my head, I know you can meet Woody, Buzz and Jesse from Toy Story. Aladdin, Jasmine, Genie and Jafar from Aladdin. Mickey and Minnie Mouse. Donald and Daisy Duck. Goofy and Pluto. Ariel and Eric from Ariel. Tiana and Naveen from The Princess and the Frog. Belle and Beast from The Beauty and the Beast. Alice, The Mad Hatter, The White Rabbit and The Queen of Hearts from Alice in Wonderland. And a bunch of others!
-One of the most popular parks and home to the ever famous "Golf Ball". This park also includes The World Showcase. The World Showcase is exactly what it sounds like, it is home to a showcase of 11 different countries. These countries include Mexico, Norway, China, France, The United Kingdom, The United States of America, Italy, Germany, Japan, Morocco, and Canada. At each country you'll find a main restaurant, showcasing that country's cuisine and a few shops that carry authentic goods from the country. In certain countries, like Norway, you can find attractions that showcase some of that country's history.
-EPCOT is also home to some very fun and famous rides. Some of these rides include Fast Track, Soarin', Mission Space, and Spaceship Earth. Most lines are tolerable besides Soarin'. Lines for Soarin' can sometimes exceed 100 minutes, so I suggest saving your fastpasses for that.
-EPCOT is also a great place to go to meet characters. You can find many of the same characters from The Magic Kingdom here as well as a few new ones including Mary Poppins.
-Perhaps the best park to go to if you're looking for pure entertainment.
-This park is home to four of Disney World's most famous, popular, and valued attractions. These, of course, are The Rockin' Rollercoaster, Toy Story Midway Mania, The Great Movie Ride and The Twilight Zone Tower of Terror. Again, these lines can be substantial if you're going during peak months so utilize your fastpasses wisely.
-While those three rides are certainly the most popular, there are many other attractions that can be considered as just as fun and entertaining. Some of these include the recently renovated Star Tours: The Adventures Continue, The Indiana Jones Epic Stunt Spectacular!, Lights, Motors, Action! Extreme Stunt Show, and a few others.
-Hollywood Studios is also home to the extremely popular Fantasmic! show.
-Dining at Hollywood Studios is also excellent. My favorite restaurants here include The Hollywood Brown Derby, Mama Melrose's Ristorante Italiano and The 50's Prime Time Cafe.
The Animal Kingdom -Home to the famous Expedition Everest one of Walt Disney World's most famous thrill rides.
-The Animal Kingdom is also home to the Kilimanjaro Safaris.
-Some other rides worth checking out include DINOSAUR, The Kali River Rapids, The Primeval Whirl, and The Wildlife Express.
-A great place to go if you love animals. I know, common sense, but it needed to be said
-Dining at The Animal Kingdom is somewhat limited and the only sit down place I can truly recommend is The Rainforest Cafe.
I know this is your first time and I know I mentioned fastpasses a few times so I'll explain those to you. The fastpass system is a system at Disney that you can utilize to essentially cut lines. The catch is that you can only get one per ticket until the fastpass is used. What happens is that for nearly every ride, there will be a fastpass kiosk. Above the kiosk there will be a "Fastpass Return" sign with two times. If the sign reads 9:40-10:40, that means you can use your fastpass between those two times. The more fastpasses are dispensed, the higher those times will climb, so get them early! If you get your fastpass for Space Mountain and your time to return is 9:40, then is soon as 9:40 hits, you can use your ticket again to get another fastpass to another ride.
I hope this was informative and I hope you enjoy your stay!