It is not that you don't need a visa. You are getting a 30 day tourist visa and you can extend it to 59 days. You can do that:
1. At the airport when you arrive. Ask and they will direct you.
2. At an immigration office before your 30 days are up.
3. Have a travel agent get it for you before your 30 days are up. They charge a fee but it it is not much.
I have only used #2 but the others are good options. If you stay at a good hotel they might directly to a travel agent who can do it.