Download the app...easy and free:
Uber 101:
Uber X=random dude in personal car...cheapest fare
Uber XL= same as X with a larger vehicle that can accommodate 4 adults
Uber Plus=Nicer towncar type service but still a personally owned car and driver
Uber Black=Towncar or better by a limo type driver
Uber SUV=Uber Black service but a larger SUV like a Suburban