The first thing you need is a passport. There are many ways of doing this but the safest way is to go old school, the United States Post Office http://www.usps.com/passport/ click on forms, get a passport and follow the steps). The passport fee is $67 and the execution fee is $30 for a total of $90. If you would like to get the passport expedited you can pay $60. Once you have obtained the passport treat it like GOLD. If you send in your form the normal way, it can take a couple months to get back. If you expedite the form, it will take about a week.
Depending on the country you go to you may need to obtain a visa. Each country has its own fee requirements to enter into its country. For example: Visas in Turkey are for visiting the country temporarily (3) months. When you step off the plane in Turkey, you go directly to the visa booth and pay $20 dollars and then go through passport control.
If you stay over the visa time limit, you will be subject to a fine, and, if you can not pay the fine, you will be banned from entering the country. Not all countries require a visa to enter into their country.
Now you are ready to fly. You may laugh at this but make sure you have a ROUNDTRIP TICKET. Call the airlines to confirm this or have an itenary sent to you via email.