It is easy for a tourist to enter the country. Depending on what country you hail from you may requiry either a Tourist Card or a Visa. A select few do not require either, but only a passport.
You will receive the form for it in the airplane or upon arrival in the country. You can also obtain them online beforehand here. At passport control you are then required to pay the $10US entrance tax and will receive the card in return.
Once you’ve got the card you can stay in the country for 30 days. If you exceed these 30 days, the penalty might get hefty.