You can find all Prague public transport information here.
For getting around Prague we suggest to buy 3 day ticket for 310CZK/cca 12,5 Euro or 24 hour for 110 CZK/approx. 4,5 Euro (it includes tram, tube and buses). You can find a detailed price list here. Tickets are available at every metro station, at most tram stations and in newspaper stores.
You can also buy the ticket by sending a text message, send: