There is  a public bus that leaves every 30 minutes to the Park, from the Bus Terminal (which is only 3 blocks from the hotel). It leaves you at the entrance to the park. Once there you just pay the entrance and you can organize yourself....

The easiest way to get there, is by taxi, because by bus, you should change buses, do the deals in the border by your own, and wait a few minutes on the road, wich is not recomended in Brazil. But of course you have bothe options....