If you are older than 15 years and medically fit, you can obtain a Student Pilot Licence. This will entitle you to fly with an instructor and by your self (solo) with authorisation from an instructor.
To obtain a Private Pilot Licence you need to be at least 17 years old, medically fit have a Student Pilot Licence and have completed the Private Pilot Licence course (theory and minimum of 40 hours flying). This will entitle you to fly an aircraft that you are rated on, with passengers, during the day and in clear weather, without charging for your services.
To charge for your services you have to have a Commercial Pilots Licence and work for a commercial operator(e.g. a charter company).