high speed train from shanghai to goungzhou

there is no high-speed but only express and fast trains from Shanghai to Guangzhou.
it takes 18 - 22 hours, and costs CNY350 for a hard-sleeper ticket.
upon arrival in shanghai, you can book the tikcet at the ticket office in the airport or at the railway station. but i suggest that you book the ticket in advance as tickets of hot route (like this one) are sold out several days before departure. to make sure you have a smooth trip, you'd better book the tikcet in advance.
you can book with this site and then collect the tikcet at the ticket office of Shanghai Pudong airport or at Shanghai railway station before departure.