On the homepage, enter your destination and trip dates and click "Go". This takes you to the "Booking" page where you'll choose your desired hotel class: 2-star, 3-star, or 4-star. The price you see is the price you will have paid after you match with a roommate.
Star ratings are determined either by hotel regulating bodies or are self-reported by the hotel. In general, 2-star hotels are comfortable and affordable with few amenities. 3-star hotels are more spacious and have additional on-site amenities like fitness centers and room service. And 4-star hotels are luxurious and upscale and offer superior service.