Let me expand a little bit here.
Take the 528 as mentioned to exit 1 which is International Drive. At the bottom of the ramp, turn left and proceed 2 traffic lights to Central Florida Parkway and turn left.The main entrance is about 1/2 mile or so down the road. Cant miss it. Has a big statue of the Whales and the BEC eagle on the lawn.
Dont bother with the prepaid sunpass. If you buy it and activiate it before noon, it will become active after 4pm.If afternoon, then 6am the next morn. Thats from the sunpass site.
To go from Sea World to the Contemporary, as you exit the parking lot, turn left, and proceed to Central Florida Parkway and turn right. Stay in the left lane as this will take you on to I4. Get off at the Epcot exit,(I want to say this is exit 75ish not sure on the number.Its the second exit you will come to.First is 535/Lake Buena Vista) and get in the left lane. That will be Epcot Center Drive. As you pass the Epcot parking entrance, the road will open from 1 lane to 2, get in the right lane, and take the MK exit. This will put you on World drive. Stay to the right and go thru the farthest right open toll lane. Then get all the way oer to the right, and stay there. You will pass the MK parking lot, TTC, go under a waterbridge, and the light after the waterbridge is the Contemporary entrance on the right.