As a youngster you can travel within Europe with one single train pass. You only need to decide from which country you are going to departure, for how many days you are planning your trip and which countries you would like to visit.
Tickets starts from 5 days till 1 month and you can buy them througly from your country. For instance you can start you trip from Turkey, Istanbul and finish in Madrid, Spain.
For more information about tickets and prices please check:http://www.interrail.eu/interrail-passes/interrail-global-pass
You can find InterRail Pass map in following links.
Have a nice trip!