Welcome to Orlando! You'll probably be tired, not feeling too great. But, the worse part is over. You're nearly there!
After you get off the plane, you'll have to go through US border control. You'll need your immigration form given to you on the flight, and your passports. Orlando International in particular has begun to use automated machines, if you're comfortable you can use them to get through quicker.
They will take your photos, get your fingerprints, check your ESTA was accepted, and then stamp your passport. The US border control staff are very serious, as they are doing a very serious job, but they are friendly people and you can talk with them or raise any questions.
DO NOT TAKE ANY PICTURES
Do not even think about getting a camera out until you're passed security and outside. We were once just through security and noticed a flash in the queue behind us, and they stopped everything. The huge massive room came to a complete standstill. And they were demanding whoever took that picture to own up so they can make sure its deleted. They stopped everyone from going through security until that person owned up. We weren't allowed to stay to watch, as were already through. Just a bit of advice, don't be that person.
At Orlando International, once you're through border control, you grab your luggage, head onto the monorail which takes you to the main building, you then go downstairs and find your travel agent kiosk, or the magic express if you have that booked.
At Sanford, once you're through border control, grab your luggage, head outside, cross the road and you'll find all the travel agent kiosks.