Research the city of Rome and the outdoor music festivals they have available. Given the distance you likely must travel, plan several activities and concerts to make your trip worth the distance.
Apply for a passport, or update the one you currently have, including the photo. You need this to travel outside the country.
Plan an itinerary of outdoor concerts you want to see, keeping in mind time and financial factors. This will help you make final travel plans.
Contact your regular airline or travel agent, or look online for flight prices and availability of flights to Rome Fiumicino or Rome Ciampino--Rome's two international airports. Book early to get the best prices.
Contact hotels in Rome, or go online to research options available. Choose something within a comfortable distance to the venues you wish to attend and sights you wish to see.
Convert your trip money from U.S. dollars to euros. Contact your bank or local post office for assistance in doing this and to get preferred conversion rates.
Check into your hotel upon arriving in Rome. Get familiar with the area, noting where you are at all times so you don't get lost.
Go to the concert location an hour or two before the show so you can soak in the culture of the area and pick the best spot to watch the concert. You may need to bring a blanket or something to sit on, as not all venues have permanent seating.