Parkour is done by using movements, such as vaulting and climbing, to navigate through and around obstacles. It can be practiced anywhere with obstacles, either natural or man-made.
Basic parkour skills include balancing, running, jumping, moving on all fours and landing properly. Balance is developed by standing and moving on narrow objects, like rails. Parkour requires the endurance to run for long periods of time, and sprinting ability when speed is necessary. Proper jumping technique is developed by learning a normal jump from a standing position, then practicing precision jumps to land on a specific spot, and finally learning how to jump correctly when running. Moving on all fours teaches coordination and exercises the entire body. It is also used when going underneath obstacles.
Landing is best accomplished by landing on two feet, then bending the knees to absorb the impact. Landing should be practiced by jumping from gradually greater heights, to get the body used to the impact of landing. It's important to practice each movement correctly and gradually build up to more-advanced techniques.
Parkour groups are a good way to practice with more experienced athletes. Additionally, meet-up groups can be found online, and some gyms also teach parkour techniques.