Who decided what the Bible was to me made up of and when did they decide it? The Disciples I imagine, right?
It was a gradual process. About 90% of our current NT cannon was universally acknowledged as scripture by the end of the first century. The first written listing of the cannon which is included in most modern bibles was by Althanasius in the 4th Century.
The Apostles decided upon the composition, and of course they wrote (or dictated) most of the books of the New Testament.
No merely old book gets to be a Gospel or part of the Bible: it has to have been accepted by the authority of the Church.
There are various gnostic ‘gospels’ - they are not actual Gospels. They (for instance) contain crazy stories about the young Christ turning his friends into bread and baking them in an oven. As you can guess: the gnostic ‘gospels’ are made-up nonsense and have no validity.
What disciples?