Arent,
How wonderful a young person such as yourself is interested in spirituality and religion! Take it as a wonderful compliment from the universe that you have been gifted with a soul and mind that is capable of such a decision and interest at such an early age!
One becomes a Baha'i at whatever moment he or she believes in their heart that Baha'u'llah is a Manifestation of God. That's all it takes. You may already be a Baha'i!
There is a procedure by which a person "enrolls" in the Baha'i Faith. In most countries there is a card one fills out called a "Delaration Card" on which one signs his name "declaring" himself as a Baha'i, and acknowledging his belief in Baha'u'llah, and understanding that there are laws to be obeyed and Insitutions to give allegience to (these being the Local Spiritual Assemblies, the National Spiritual Assemblies, and Universal House of Justice). That card is then given to the nearest Local Spiritual Assembly in your area. But really, you are a Baha'i the moment you believe in Baha'u'llah!
I know many young people have parents that are trying to raise them to be a particular religion. And while Baha'u'llah has said that no family member has a right to force another to be a particular religion, He has also told us that we must obey are parents and respect them. If for some reason your parents don't want you to become a Baha'i
, you should respect them and officially join the Faith when you get a little older (but really no one can tell you what is in your heart anyway, so even if you have to wait a while, you can still be a Baha'i inside your soul
). But hopefully your parents are encouraging you to seek the Truth in all places and will be supportive of your interest in the Baha'i Faith.
You can easily buy official Baha'i books and Baha'i Scripture (and probably calendars too) from:
http://www.bahaibookstore.com/
If you don't have money to buy books, or you can't wait to start reading, you can find most all of the important Baha'i books online to read or download onto your computer at:
http://reference.bahai.org/en/
And you can find accurate information about the Baha'i Faith from an official informational website at:
http://www.bahai.org/
You can also find many local Baha'i communities with small lending libraries and bookstores of their own (many local Baha'i communities have listings in the white pages phone books).
Oh, and there is a special offical Baha'i website for young people at:
http://www.bahaiyouth.com/
If your friend is a Baha'i he or she can probably introduce you to other Baha'is in the area who might have books you can borrow.
As well as reading books "about" the Baha'i Faith by Baha'is and non-Baha'is which you have already done, I urge you to read some of the Scripture of the Baha'i Faith, the actual Writings of Baha'u'llah and 'Abdu'l-Baha (especially "The Hidden Words" and "Some Answered Questions"). And definately get a copy of a Baha'i Prayerbook and read prayers every day and see how they make you feel happier and able to treat people nicer, and how you don't get upset at things so much. In otherwords, the proof in the Baha'i Faith is found in how Baha'u'llah's Writings change you for the better. It's called "the Creative Word" because it can recreate you into a better happier person!
You should know that you will find people that want to help you, and you will find people that want to stop you from seeking the Truth. Just smile and thank them all and continue on your own personal journey of discovery!
Good luck on your journey!
-jpd