The Inca Trail is a 3-4 day trek that takes you from kilometer 88 (Ollantaytambo) to the top of Machu Picchu. You can do this on your own (cheap, but you must bring all with you) or in organized tour to some of the agencies in Cusco (a lot of them): they are responsible for porters, food and more. Either way, you pay entry (there are controls). The last day was up early and goes out at night (04.00) to reach the Puerta del Sol, where see the sunrise over the ruins. A lifetime experience!